Enhancement: Rework mobile navigation

The navigation for mobile devices <640px has been reworked.

https://github.com/owncloud/web/issues/8557
https://github.com/owncloud/web/issues/7253
https://github.com/owncloud/web/issues/3774
https://github.com/owncloud/web/issues/9073
https://github.com/owncloud/web/pull/8757
https://github.com/owncloud/web/pull/9074
