feat(dav): implement event to trigger updating the resources/rooms cache

[st3iny]

• Resolves: none

Summary

Ref nextcloud/calendar_resource_management#124

Provide a public event and listener to allow updating rooms and resources (almost) instantly instead of waiting up to an hour.

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)

[ChristophWurst]

Suggested change

	class ScheduleResourcesRoomsUpdateEvent extends Event {
	class ScheduleResourcesRoomsUpdatedEvent extends Event {

the event should signal that something happened, not the intent

https://docs.nextcloud.com/server/latest/developer_manual/basics/events.html#naming-scheme

[ChristophWurst]

To make this a real public API we can move the events to OCP\Calendar\Resource

As an alternative to the event approach you could also consider an explicit method on \OCP\Calendar\Resource\IManager.