GROOVIE: More work on transparency in the puzzle scenes for V2 games

This fixes most of the transparency issues in the puzzle screens.
They are still not correct, as the relevant videos play completely,
instead of showing a single frame. This also fixes issues with commit
2d42ab8
GROOVIE: Handle flag 2 for V2 games (show a whole overlay video)
GROOVIE: More bugfixes for V2 puzzle overlay videos
GROOVIE: Handle transparency in Gamepad videos in the 11th Hour
Merge https://github.com/scummvm/scummvm