Sync global marks

[oysandvik94]

I was thinking of implementing this in a hook in my own config, but maybe it's relevant for core functionality:

Global marks will point to the file in the branch you're in, so if you switch worktree, then your global mark will be useless essentially.

I was thinking of just storing the marks with the worktree, and updating the marks when worktree switches.

[polarmutex]

I will look into this