[android] #5285 - bring selected MarkerView to the front

Fixes #5285

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/annotations/MarkerViewManager.java

@@ -210,6 +210,7 @@ public class MarkerViewManager {
                 mapboxMap.selectMarker(marker);
             }
             marker.setSelected(true);
+            convertView.bringToFront();
         }
     }
 

platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/annotation/MarkerViewActivity.java

@@ -55,7 +55,8 @@ public class MarkerViewActivity extends AppCompatActivity {
             new LatLng(38.909698, -77.029642),
             new LatLng(38.907227, -77.036530),
             new LatLng(38.905607, -77.031916),
-            new LatLng(38.889441, -77.050134)
+            new LatLng(38.889441, -77.050134),
+            new LatLng(38.888000, -77.050000) //Slight overlap to show re-ordering on selection
     };
 
     @Override