Block occ commands when in maintenance mode

[miaulalala]

Summary

Currently, occ allows execution of commands even while in maintenance mode. The CLI does warn the admin that commands are limited but the execution still works.

This PR adds an exception to block any command that isn't maintenance:mode --off or status as executing other commands is unsafe.

(Either this, or remove the misleading sentence as commands can be executed and the database is indeed available - occ user:add for example works).

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[miaulalala]

Alternative PR by Daniel here: #37178

[nickvergessen]

We have quite some commands in the docs where we recommend to put the instance into maintenance before (and even turn off the webserver), so I think it's intended that it still works :/

Long running and expensive things like:

• Add missing index
• Add primary key
• Convert to utf8mb4

And so on come to mind.

[miaulalala]

We have quite some commands in the docs where we recommend to put the instance into maintenance before (and even turn off the webserver), so I think it's intended that it still works :/

Long running and expensive things like:

• Add missing index
• Add primary key
• Convert to utf8mb4

And so on come to mind.

Then Daniel's version is the superior approach. Closing this then.