This PR implements a confirmation popup on the Domain settings page when
a user attempts to save a subdomain change.
- When the user saves the updated subdomain, a confirmation modal is
shown.
- The modal informs the user that changing the subdomain will log them
and all other users out.
- If the user confirms, the subdomain change proceeds as normal.
- If the user cancels, the update is aborted and no changes are made.
### Demo
https://github.com/user-attachments/assets/dcea51c8-ffd2-40ca-bc75-0c0228df5344
Related Issue
Closes#11741