lock: add clear all notifications button

[acastaneiras]

Adds functionality to clear notifications from the lock screen.

Changes:

• Add clear all button in notifications header (right side).
• Add delete notification groups on middle click press.

Video (for some reason the cursor doesn't want to be recorded):

Video_2025-11-04_19-03-40.mp4

[AleksElixir]

Could it also be made dissableable in the shell.json, I wouldnt rly want someone to clear all my notifs when im away from my pc

[acastaneiras]

Could it also be made dissableable in the shell.json, I wouldnt rly want someone to clear all my notifs when im away from my pc

you're right, made it configurable with an option. disabeled by default.