Customized user navigation to include most used Lichess features

[jalpp]

The current user navigation only contains static content like settings board perfs etc. if in settings we could customize this menu to have puzzles and studies for quicker navigation. Especially have “My Studies” and “My Puzzle Dashboard” and “My Friends” in there so users can easily navigate to their studies, games and puzzles quicker. For mobile browsers it’s quicker and better experience than to navigate to specific feature and select “My”