untangle different user manager instances, fixes #22770

Remove browser autocomplete in new file menu

Minor grammar in config.sample.php

Fix this here in the source so it will propogate into the documentation.
Edit was already applied in https://github.com/owncloud/documentation/pull/2208 but needs to be done here at the source.

Translate strings of federation admin section

Add Versions app header to config.sample.php

Master is now 9.1

Update copyright information and author file

Exclude custom data directory from integrity checker

allow putting the part file in the view root

Use readiness notification socket to be absolutely sure this works

Probably nice for the people that contributed to 9.0 to see themselves in the AUTHORS file :)

We should not scan any custom data directory in the integrity checker as well. Otherwise this would lead to a massive increased update time that may likely exceed the timeout.

To test this:

1. Install ownCloud 8.2.2, set as data dir another folder than `data` such as `data-asdf`. Make sure that folder lives in the web root as well.
2. Update that instance to 9.0.0 beta2 => Errors are shown in the code integrity check
3. Apply this patch and trigger the rescan in the admin settings => No errors are shown anymore (can also do a new update with that patch applied)

Fixes https://github.com/owncloud/core/issues/22698

Checksum intergration tests and fixes

remove remote address book if access was revoked

We should also store checksums on chunked files.
We do not checksum individual chunks but only the final file.

When we overwrite a checksumed file with a file without a checksum we
should remove the checksum from the server.

This is done by setting the column to empty.

* Upload file with checksum
* Chunked upload with checksum
* Copy file with checksum should also copy the checksum
* Moving a file with checksum should also move the checksum
* Uploading a file with checksum and overwriting it with a file without cheksum should remove the checksum

Add autodiscovery support to server-to-server sharing implementation

use ocs discover endpoint to test remote

Disable app that bricks the server after enabling