Hard to close Planner Settings modal on mobile

[kokrui]

Is your feature request related to a problem? Please describe.

On mobile, on the Planner page, the settings modal may not be easy to close on some screens, as it requires the user to tap on the space outside of the modal.

I think a good solution would be to add a close button at the top-right like the "Beta - Send Feedback" modal does:

I think it's fine if the close button appears on both mobile and desktop too

IMO this is NOT a blocker for #3696