Fix the Safe area conflict for material controls in Android

[MadGeorge]

The issue:

When a player widget is used inside a scaffold with extendBodyBehindAppBar set to true on a Scaffold, the progress bar and the fullscreen button go out of the player bounds which breaks the layout and makes them inaccessible for a user's input.

Example from real app:

extendBodyBehindAppBar: true, controls are falling down

extendBodyBehindAppBar: false, controls are fine, but we need the content of the screen go under the app bar

extendBodyBehindAppBar: true, and the fix from PR This is how it should work.

If I got it right the issue is Android/Fucsia related, since MaterialControls do not used for others. This was not tested on Fucsia.