Implement visiting Criterion\UserMetadata::GROUP target

This PR resolves https://jira.ez.no/browse/EZP-23400

Ancestor UserGroups ids for the Content owner are indexed and criterion visitor for `GROUP` target is implemented.

Not that this will require reindexing owner user Content when:

1. Additional Location for owner user is added
2. User Location (or subtree) is moved
3. Parent user Location is swapped
4. possibly more...

We currently do not implement slots for all of the cases, hence the tests for Solr and ES are intentionally limited until we implement them. We also lack SPI to do implement some of those properly. UserService handles this problem by relying on search, but search should not be used in indexing slots as indexing is asynchronous.

Tests: integration tests.