[RSDK-9879] - Make datamanger sync dep implcit

[seanavery]

Description

When I first wrote video-store, I did not understand implicit dependencies, so just fixing this now. Also, a user recently wanted to use the module without a sync service so wanted to make that possible.

• Gets rid of hacky explicit datamanager dep check.
• Supports implicit datamanager dep.
• Makes sync attribute optional.

Tests

• Added automated config tests ✅
• Manual tests:
  • Implicit sync dep succeeds ✅
  • Missing sync attr succeeds ✅
  • Mis-named sync dep fails ✅
  • Sync attr with no service fails ✅

[randhid]

Oh, I too thought data manager could only be added as an explicit dependency.

Heads up - data manager is special - it uses weak dependencies, which are prone to reconfigure loops especially when data manager weakly depends on a component and the component implicitly depends on data manager, creating a cycle, please test with the full suite (re-id, event manage, video store viamrtsp) config for this config change. If it makes it reconfigure in a loop too often.

Because this requires a lot of testing, I'd rather you focus on the rtp passtrough poc. I know this seemed like a quick win, but you're playing with the most finicky part of our dependencies stack here.

[hexbabe]

Code LGTM

Also what Rand says makes sense for extra carefulness