Enhancement: Reorganize urls

with the [global-url-format ADR](https://github.com/owncloud/ocis/blob/master/docs/ocis/adr/0011-global-url-format.md) we've decided how the internal
and external URL schema should look like.

To have a human understandable structure we've decided to also rethink how the overall structure should look like.
This PR introduces the new schema and takes care that existing routes still work by redirecting them.

https://github.com/owncloud/web/pull/6137
https://github.com/owncloud/web/issues/6085
https://github.com/owncloud/ocis/blob/master/docs/ocis/adr/0011-global-url-format.md
