Sync on collection update

[sunkup]

Purpose

Nice to have for:

• When a collection gets enabled you would usually always want to sync it right away.
• Force-read-only setting: gets set/updated at sync only (see "Force read-only" setting not effective immediately #851).

Short description

• Pass account of the changed collection along when notifying listeners of collections change.
• Then have SyncWorkerManager listen to any collection changes and use the account passed along to
• then trigger a short delay-coroutine job, which resets itself on new change observations and after delay expiration
• enqueues a one time sync of the whole account (not just the service which the collection belongs to - although that would prob be possible as well).

Checklist

• The PR has a proper title, description and label.
• I have self-reviewed the PR.
• I have added documentation to complex functions and functions that can be used by other modules.
• I have added reasonable tests or consciously decided to not add tests.

[rfc2822]

I wonder how this behaves when the services are refreshed. Doesn't it enqueue a lot of syncs during service detection (whenever a collection is updated)?

My ideas (may or may not make sense):

• A delay of a few seconds between the collection change and the sync (like for the push registration) could at least reduce the number of synchronizations during service detection.
• Or maybe pause it somehow?
• Maybe separate callbacks for the actions we want to observe (update read-only, update sync flag)? Has advantages and disadvantages.