owncloud/core

Change: Don't report locking support in public.php and public-files endpoints

Public endpoints were reporting locking support even though the backend was rejecting
those requests. This was causing a problem accessing a publicly shared document using
LibreOffice opening the file through webdav (LibreOffice was complaining about a
Forbidden error trying to lock the file)

With these changes, LibreOffice will show a warning while opening the remote file (from
a public link) if the file is already locked, letting the user choose what to do. If there
is no lock, the file will be opened normally, but it won't be locked.

The following changes are expected:
* LOCK and UNLOCK methods won't be reported as allowed
* Lock information (d:lockdiscovery) and support (d:supportedlock) will be shown in the
  propfind if requested (lock support is needed for LibreOffice to try to lock the file)
* Trying to lock the file through the public link will either throw a Locked exception if there is
  a lock in place, or MethodNotAllowed if there are no locks (the Locked exception is needed
  for LibreOffice to show a popup warning the user that the file is locked)


https://github.com/owncloud/core/pull/36402