Allow to set empty status message

[timkrueger]

Allow to set a empty status message in the set status view.

Because of an API issue currently it is no allowed to set an empty status message. If the status message text field is empty, the Set status message button is disabled.

This workaround was introduced with https://github.com/nextcloud/talk-android/pull/1841

This issue is blocked by https://github.com/nextcloud/server/issues/31452