Minor refactoring of dynamic patching code. (#7325)

Minor refactoring of dynamic patching code.

- Changes naming of manifest properties to be consistent with documentation.
- Moves methods from inner class to outer class to make them more reusable.

Author: sbaranov

shell/platform/android/io/flutter/view/FlutterMain.java

@@ -264,7 +264,7 @@ private static void initResources(Context applicationContext) {
             Log.e(TAG, "Unable to read application info", e);
         }
 
-        if (metaData != null && metaData.getBoolean("DynamicUpdates")) {
+        if (metaData != null && metaData.getBoolean("DynamicPatching")) {
             sResourceUpdater = new ResourceUpdater(context);
             sResourceUpdater.startUpdateDownloadOnce();
             sResourceUpdater.waitForDownloadCompletion();