Adding warmup call API for Settings search ranking.

- This allows the ranking implementations to prepare for predictions and
avoids latency on the first prediction call.

Bug: 38197948
Bug: 37312700

Test: RunSettingsRoboTests

Change-Id: I1878b14765ad7cede5648fa1c7f29c419c2e5535

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

@@ -130,4 +130,10 @@ public interface SearchFeatureProvider {
         return false;
     }
 
+    /**
+     * Prepare for search ranking predictions to avoid latency on the first prediction call.
+     */
+    default void searchRankingWarmup(Context context) {
+    }
+
 }