Support installing translations for all installed plugins/themes

[ocean90]

See #59.

[ocean90]

@schlessera provided some feedback on Slack for this: https://wordpress.slack.com/archives/C02RP4T41/p1539759949000100

tldr; Consider using a table for the output which should make it easier to parse the result of each installation.

[ocean90]

Current output is inspired by wp plugin update --all:

wp language plugin install --all de_DE de_CH

Warning: Language 'de_DE' not available.
Language 'de_DE' for 'Airplane Mode' not installed.
Warning: Language 'de_CH' not available.
Language 'de_CH' for 'Airplane Mode' not installed.
Downloading translation from https://downloads.wordpress.org/translation/plugin/akismet/4.0.3/de_DE.zip...
Unpacking the update...
Installing the latest version...
Translation updated successfully.
Language 'de_DE' for 'Akismet Anti-Spam' installed.
Downloading translation from https://downloads.wordpress.org/translation/plugin/akismet/3.1.11/de_CH.zip...
Unpacking the update...
Installing the latest version...
Translation updated successfully.
Language 'de_CH' for 'Akismet Anti-Spam' installed.
Language 'de_DE' for 'Classic Editor' already installed.
....
Warning: Language 'de_CH' not available.
Language 'de_CH' for 'WP Team List' not installed.
Language 'de_DE' for 'WP Team List' already installed.
Language 'de_CH' for 'WP Team List' already installed.
Language 'de_DE' for 'WP Widget Disable' already installed.
Language 'de_CH' for 'WP Widget Disable' already installed.
+---------------------------------+--------+-------------------+
| name                            | locale | status            |
+---------------------------------+--------+-------------------+
| airplane-mode-master            | de_DE  | not available     |
| airplane-mode-master            | de_CH  | not available     |
| akismet                         | de_DE  | installed         |
| akismet                         | de_CH  | installed         |
| classic-editor                  | de_DE  | already installed |
| classic-editor                  | de_CH  | not available     |
....
| rplus-wp-team-list-git          | de_DE  | not available     |
| rplus-wp-team-list-git          | de_CH  | not available     |
| wp-team-list                    | de_DE  | already installed |
| wp-team-list                    | de_CH  | already installed |
| wp-widget-disable               | de_DE  | already installed |
| wp-widget-disable               | de_CH  | already installed |
+---------------------------------+--------+-------------------+
Success: Installed 2 of 86 languages (84 skipped).

wp language plugin install --all de_DE --format=summary

Warning: Language 'de_DE' not available.
Language 'de_DE' for 'Airplane Mode' not installed.
Language 'de_DE' for 'Akismet Anti-Spam' already installed.
Language 'de_DE' for 'Classic Editor' already installed.
Warning: Language 'de_DE' not available.
Language 'de_DE' for 'Core Control' not installed.
Warning: Language 'de_DE' not available.
Language 'de_DE' for 'CSS' not installed.
....
Language 'de_DE' for 'WP Team List' not installed.
Language 'de_DE' for 'WP Team List' already installed.
Language 'de_DE' for 'WP Widget Disable' already installed.
Success: Installed 0 of 43 languages (43 skipped).

wp language plugin install --all de_DE --format=json

[{"name":"airplane-mode-master","locale":"de_DE","status":"not available"},{"name":"akismet","locale":"de_DE","status":"already installed"},{"name":"classic-editor","locale":"de_DE","status":"already installed"},{"name":"core-control","locale":"de_DE","status":"not available"},{"name":"css","locale":"de_DE","status":"not available"},{"name":"debug-bar","locale":"de_DE","status":"not available"},{"name":"debug-bar-console","locale":"de_DE","status":"not available"},{"name":"debug-bar-transients","locale":"de_DE","status":"already installed"},{"name":"disable-privacy-tools","locale":"de_DE","status":"already installed"},{"name":"drafts-of-post-revisions","locale":"de_DE","status":"not available"},{"name":"dynamic-hostname","locale":"de_DE","status":"not available"},{"name":"genericond","locale":"de_DE","status":"not available"},{"name":"gutenberg-git","locale":"de_DE","status":"not available"},{"name":"gutenberg","locale":"de_DE","status":"already installed"},{"name":"gutenberg-testing","locale":"de_DE","status":"not available"},{"name":"test-plugin","locale":"de_DE","status":"not available"},{"name":"h2push","locale":"de_DE","status":"not available"},{"name":"members","locale":"de_DE","status":"already installed"},{"name":"ms-global-media","locale":"de_DE","status":"not available"},{"name":"o2-git","locale":"de_DE","status":"not available"},{"name":"parent-term-toggler","locale":"de_DE","status":"not available"},{"name":"polylang","locale":"de_DE","status":"already installed"},{"name":"preserve-editor-scroll-position","locale":"de_DE","status":"not available"},{"name":"public-post-preview-git","locale":"de_DE","status":"not available"},{"name":"public-post-preview","locale":"de_DE","status":"already installed"},{"name":"query-monitor","locale":"de_DE","status":"already installed"},{"name":"relax-comment-filters","locale":"de_DE","status":"not available"},{"name":"rest-post-likes","locale":"de_DE","status":"not available"},{"name":"rewrite-rules-inspector","locale":"de_DE","status":"not available"},{"name":"shiny-updates","locale":"de_DE","status":"not available"},{"name":"shortcode-ui","locale":"de_DE","status":"already installed"},{"name":"slack","locale":"de_DE","status":"not available"},{"name":"solr-power","locale":"de_DE","status":"not available"},{"name":"user-switching","locale":"de_DE","status":"already installed"},{"name":"woocommerce","locale":"de_DE","status":"already installed"},{"name":"wordpress-importer","locale":"de_DE","status":"already installed"},{"name":"wordpress-importer-git","locale":"de_DE","status":"not available"},{"name":"wp-feed-post-thumbnail","locale":"de_DE","status":"already installed"},{"name":"rest-api","locale":"de_DE","status":"not available"},{"name":"rest-api-oauth1","locale":"de_DE","status":"not available"},{"name":"rplus-wp-team-list-git","locale":"de_DE","status":"not available"},{"name":"wp-team-list","locale":"de_DE","status":"already installed"},{"name":"wp-widget-disable","locale":"de_DE","status":"already installed"}]%

Let me know what you think. If it's good I'm going to do the same for themes and add some tests.

[ocean90]

(The command:language-core-install label should probably be removed as the PR only touches plugins and themes.)

[schlessera]

@ocean90 What do you think about combining these two in the "live status messages" (not the table):

Warning: Language 'de_CH' not available.
Language 'de_CH' for 'WP Team List' not installed.

This would then turn into this instead:

Warning: Language 'de_CH' for 'WP Team List' not available.

This already implies that it will not be installed.

Would this make it clearer, or does it worsen overall consistency?

[schlessera]

Otherwise, I like the current version and think this is good to go.

[ocean90]

What do you think about combining these two in the "live status messages"

The output next to "Warning" is just one of the WP_Error messages which download_language_pack() can return. We could extend the changes from #69 to also adjust the logging but not sure if it's really worth since it would only cover one case. Maybe worth it's own issue/PR.