Gallery should implement full screen / edge-to-edge for Android Q+ devices

[shihaohong]

Currently, flutter_gallery shows a black bar on the bottom of the screen where the system gestures are for Android Q+. However, the recommendation by Android suggests that we should now be making the system navigation bar transparent to take advantage of the entire screen.

What it looks like now:

What it should look like:

[Zee2]

Any update on this, 1.5yr later? See flutter/flutter#69999

[Piinks]

I am not actively working on this migration right now, so I am going to un-assign myself. The necessary changes have landed, so it is possible to implement this in the gallery if anyone would like to do so. See flutter/flutter#81303