This PR moves the `CollabNotification` component from the collab_ui
crate to the UI crate, so that we can add a component preview to it. It
also fixes problems with text truncation and other little details.

<img width="700" height="1674" alt="Screenshot 2026-01-29 at 4  07@2x"
src="https://github.com/user-attachments/assets/6aca6cff-564a-4729-b505-c02d8c3af97f"
/>

Release Notes:

- Collab: Fixed overflowing text in project sharing and call
notifications.