[web] Add admin permission `modify-user-name` (#27284)

* Add capabilitiy `modify-user-name`

* Check `modify-user-name` (backend)

* Check `modify-user-name` (frontend)

* Add `isAdmin: true` in UserAdminController.test.mjs

* Disable the name inputs instead of hidding them, so admins can still see them

* Update tests

* Update services/web/modules/admin-panel/test/unit/src/UserAdminController.test.mjs

Co-authored-by: Andrew Rumble <andrew.rumble@overleaf.com>

---------

Co-authored-by: Andrew Rumble <andrew.rumble@overleaf.com>
GitOrigin-RevId: 8731a57aaea8960606ecb4ecd5094eef4fb86f89

services/web/types/admin-capabilities.ts

@@ -1,6 +1,7 @@
 export type AdminCapability =
   | 'clear-saml-data'
   | 'modify-user-email'
+  | 'modify-user-name'
   | 'view-project'
 
 export type AdminRole =