Follow-up of https://github.com/zed-industries/zed/pull/30015

Merges suppress and close buttons into one, with `shift` changing the
state and showing different tooltips.
Currently, there's no tooltip for notification suppress action, hence
none is displayed in the video:


https://github.com/user-attachments/assets/678c4d76-a86e-4fe9-8d7b-92996470a8a8

Release Notes:

- N/A