Improve handling of different URLs. From now on we will allow to
configure:
- wopi_url Used by Nextcloud to connect to Collabora in the backend
- wop_callback_url Passed to collabora to connect back to Nextcloud
(optional, determined from the browser URL if not set)
The public_wopi_url which was only partly working is no longer ment to
be manually set and will be overwritten depending on the
/hosting/discovery response.
Further this PR improves:
- Add setup check on occ and admin page
- Give proper error on individual failures of the setup check
- Display configured and detected URLs to make setup issue debugging
easier
- Refactor services to have a cleaner structure for setup checks,
discovery and capabilities fetching
Signed-off-by: Julius Härtl <jus@bitgrid.net>
