game_engine. Change game engine NDK target platform to android-14.

Also fix a build issue in when instrument log is enabled.
game_engine. Add test game tree.
game_engine. Fix to shader manager shader access.

The shader access code still used hard coded shader used in the test game.
Remove the hard coded shader access, and repalce with loading shaders from resources.
game_engine. Update to test game assets.

Add assets sources dir - holds the test game xml tree.
Add simple shaders.
game_engine. Fixes to test game simple shaders.