Migrate from Plugin SearchTarget to API search Target [3/3]

- Implement SearchServicePipeline which utilizes system Search services for AllAppsSearch Results
- Parse android.app.search.SearchTarget handling for Shortcut, Slice, Settings and Play results
- Aggregate SearchTargets to a tree structure for in-line Search Results

Bug: 177223401
Test: Manual
Change-Id: Iddc0f3691578fd332cd2df643a237b29f3eccd0d