Implement SearchDataService.getSearchResults in Kotlin Picker

* Replace FakeSearchDataServiceImpl with the actual implementation

* Implement getSearchResults() in SearchDataService

* Create a SearchResultsPagingSource that is reponsible to load items
  from the Picker Backend in pages

* Create a new search request and trigger search results sync in the
  backend.

* Refresh data when the available providers change

Bug: 374920933
Test: atest SearchDataServiceImplTest
Test: atest MediaProviderClientTest
Change-Id: I743a91152779ad8f04967420f0ec18df8c74c123
Flag: com.android.providers.media.flags.enable_photopicker_search