Updating the search ranking API and some improvements:

- Ranking API is modified to run the ranking asynchronous to the main thread.
Therefore, it can now run in parallel to loading the results from DB
which decreases the overall latency.
- Ranking API now supports reporting failure from the ranker
implementation side.
- Settings that are not ranked by the ranker algorithm are now ranked at
the end of the list. This is added for dynamic settings (e.g., apps).
- Failure handling mechanism is added for cases that ranker catches an
exception or it takes a long time to respond.

Bug: 37312700
Fixes: 36866337
Fixes: 36867476
Fixes: 36866736
Fixes: 36866838

Test: RunSettingsRoboTests

Change-Id: I3a2a97e3a07a8d4afbb090061d92172a27588ee7

tests/robotests/src/com/android/settings/search/IntentSearchViewHolderTest.java

@@ -97,7 +97,7 @@ public class IntentSearchViewHolderTest {
         assertThat(mHolder.summaryView.getVisibility()).isEqualTo(View.VISIBLE);
         assertThat(mHolder.breadcrumbView.getVisibility()).isEqualTo(View.GONE);
 
-        verify(mFragment).onSearchResultClicked(eq(mHolder), anyString());
+        verify(mFragment).onSearchResultClicked(eq(mHolder), any(SearchResult.class));
         verify(mFragment).startActivity(any(Intent.class));
     }