Move a11y indexing from DynamicContentMonitor to loader

This is necessary to kill DynamicContentMonitor later

- Removed all logic related to indexing accesiblitysetting from the
  monitor class and AccessibilitySetting page itself
- Created a loader to search against A11yServices at runtime

I noticed adding a loader in SearchResultsAdapter is rather manual. It's
something we should consider refactor in the future.

Bug: 64310452
Test: robotests
Change-Id: Iff31aff65ce000991229433f294e2ec69af99da2

src/com/android/settings/search/SearchFeatureProvider.java

@@ -42,6 +42,12 @@ public interface SearchFeatureProvider {
      */
     InstalledAppResultLoader getInstalledAppSearchLoader(Context context, String query);
 
+    /**
+     * Returns a new loader to search accessibility services.
+     */
+    AccessibilityServiceResultLoader getAccessibilityServiceResultLoader(Context context,
+            String query);
+
     /**
      * Returns a new loader to get all recently saved queries search terms.
      */
@@ -95,8 +101,8 @@ public interface SearchFeatureProvider {
     /**
      * Query search results based on the input query.
      *
-     * @param context application context
-     * @param query input user query
+     * @param context                     application context
+     * @param query                       input user query
      * @param searchResultsRankerCallback {@link SearchResultsRankerCallback}
      */
     default void querySearchResults(Context context, String query,
@@ -112,8 +118,8 @@ public interface SearchFeatureProvider {
     /**
      * Notify that a search result is clicked.
      *
-     * @param context application context
-     * @param query input user query
+     * @param context      application context
+     * @param query        input user query
      * @param searchResult clicked result
      */
     default void searchResultClicked(Context context, String query, SearchResult searchResult) {