High score screen enhancements

[decarbonization]

• [x] Only show high score screen when score has placement on list
• [x] Don't pre-fill name unless the user has previously entered a name
• [x] Show the score at the end of the game either on the score list (highlighted), or on the name input dialog, or both.
• [x] Move clear all to a harder to reach region of the screen
• [x] Add confirmation dialog to clear all
• [x] Add on-screen done button to high scores