Expose subscription calendars

[kesselb]

• Resolves: Events from subscribed calendar not showing up in Upcoming widget. calendar#5628

Summary

Make calendar subscriptions available via php api.

TODO

• Check getPermissions
• Tests
• PR for Calendar to increase the event limit Replaced by CalDAV fix search with limit and time range #45222

Test cases

• Add subscription
• Delete subscription
• Show/Hide/Rename subscription
• Export subscription
• Export event

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)

[kesselb]

Patch the calendar app for easier testing:

diff --git a/lib/Dashboard/CalendarWidget.php b/lib/Dashboard/CalendarWidget.php
index f1bbd231e..83d978d2d 100644
--- a/lib/Dashboard/CalendarWidget.php
+++ b/lib/Dashboard/CalendarWidget.php
@@ -144,7 +144,7 @@ class CalendarWidget implements IAPIWidget, IButtonWidget, IIconWidget, IOptionW
                        return [];
                }
                $dateTime = (new DateTimeImmutable())->setTimestamp($this->timeFactory->getTime());
-               $inTwoWeeks = $dateTime->add(new DateInterval('P14D'));
+               $inTwoWeeks = $dateTime->add(new DateInterval('P60D'));
                $options = [
                        'timerange' => [
                                'start' => $dateTime,
@@ -153,7 +153,7 @@ class CalendarWidget implements IAPIWidget, IButtonWidget, IIconWidget, IOptionW
                ];
                $widgetItems = [];
                foreach ($calendars as $calendar) {
-                       $searchResult = $calendar->search('', [], $options, $limit);
+                       $searchResult = $calendar->search('', [], $options);
                        foreach ($searchResult as $calendarEvent) {
                                // Find first recurrence in the future
                                $recurrence = null;

[kesselb]

Example calendar for testing: https://www.feiertage-deutschland.de/kalender-download/ics/feiertage-deutschland.ics

[tcitworld]

Can this expose the subscription source as well? Would be handy for nextcloud/calendar#5168 too

[kesselb]

Can this expose the subscription source as well?

Added getSource to CachedSubscriptionImpl

[ChristophWurst]

Makes sense

[kesselb]

/backport to stable29

[kesselb]

/backport to stable28

[kesselb]

/backport to stable27