Fix for ios fullscreen captions not displaying

[Dananji]

This fix overrides the native iOS player in fullscreen mode and display a similar interface of the avalon's media player. This way the captions are accessible in a similar way to the regular player.

This could be a temporary fix from a UI perspective. Related ticket: #4951

[joncameron]

This looks good to me. The fake fullscreen option seems to be a reasonable strategy to resolve the iOS caption issue right now and there's not much to change if there's a different strategy for handling this on mobile in the future.