STORM-380 FIXED Added syncing animations and sounds before the gesture starts playing.

The actual playing of animations and sounds of a gesture starts only when all needed animations and sound files are loaded into viewer cache. This reduces the delay between animations and sounds meant to be played simultaneously but may increase the delay between the moment a gesture is triggered and the moment it starts playing.

Fixed calling assets callback to clean up the void pointer in getAssetData() and avoid potential memory leaks.