Enhancement: Update ownCloud Web to v5.5.0-rc.8

Tags: web

We updated ownCloud Web to v5.5.0-rc.8. Please refer to the changelog (linked) for details on the web release.

https://github.com/owncloud/web/pull/6854
https://github.com/owncloud/ocis/pull/3844
https://github.com/owncloud/ocis/pull/3862
https://github.com/owncloud/web/releases/tag/v5.5.0-rc.8
