[200924] Added flashlight, SE & unlock animation

Added Point Light in the scene, some sound effect to Improve immersion and an animation when unlocking some items. 

Adjust some dialogs and change the style of navigation button to make it to be seen clearly.

 In the webGL version, VideoPlayer still cannot be used to play videos on Raw Image. As a result, in the main menu, video cannot be played and temporarily replaced with pictures, still looking for the solution.