Fix remaining avatar problems

Fix OCP PHPDoc

keep a read lock while scanning a file or folder

* was always a string instead of \OCP\IUser

Trim path in changeLock

Rethrow LockedException with full path

Load the update information asyncroniously to fix the page load speed

Throw exception if memcache misconfigured or missing

Convert invalid path exception to sabre exception on MOVE

Because the path is converted to md5 from the original exception,
rethrow the exception with the correct full path

Skip directory entry in S3 opendir

Reintroduce user cache

This was required by avatars and was broken with https://github.com/owncloud/core/pull/16200

Fixes https://github.com/owncloud/core/issues/16942

The result set contains the directory itself, so skip it to avoid
scanning a non-existing directory

Align recommended settings

add proper locking to file_put_contents when using streams

Fixed "p" element containing a "div" 

Compare and delete locking watch

Determine the size we need before asking for a thumbnail

Added Opus Mimetype Support

Truncate preview resolution

Webdav PUT small file lock must be shared during hooks

This aligns the recommended setting with the max-age of `15768000` as described in our documentation. Furthermore it fixes some logical problems with the code, unit tests has been added as well.

Fixes https://github.com/owncloud/core/issues/16673