Add code inspector to ensure fragments implements search.

Unless a fragment is grandfathered:
- If it's a SearchPreferenceFragment, it needs to implement Indexable.
- If it's a Indexable, it needs to contain SEARCH_INDEX_DATA_PROVIDER.

Bug: 33209410
Test: make RunSettingsRoboTests
Change-Id: I078c54374341ba2966145429fc1507a3d5763d3b