Split IntelligenceManager / IntelligenceService.

This name is too generic, so we split it in 2 parts:

- ContentCaptureManager: the public API used by views and apps to report their
  structure.
- SmartSuggestionsServiec: the system service use to consume these events and
  provide autofill suggestions.

This CL also:

- Optimizes ContentCaptureManager allocation so they are not created on contexts that are not
  capturing events (such as views from the system server).
- Uses a generic ContentCaptureEventsRequest (rather than a list of events) to make it easier
  to be extended.
- Fixed IntelligencePerUserService so it clears the sessions when the
  implementation changes.

Test: manual verification

Bug: 119776618
Bug: 117944706
Bug: 119638877

Change-Id: I069bcd23dda94afe18b2781fd3981b8b555afa56