Change silences to always require approval on follow (#11975)

* Change silenced accounts to require approval on follow

* Also require approval for follows by people explicitly muted by target accounts

* Do not auto-accept silenced or muted accounts when switching from locked to unlocked

* Add `follow_requests_count` to verify_credentials

* Show “Follow requests” menu item if needed even if account is locked

* Add tests

* Correctly reflect that follow requests weren't auto-accepted when local account is silenced

* Accept follow requests from user-muted accounts to avoid leaking mutes