Enhancement: Enable search all files for ocis backend

We've enabled the search all files feature for ocis backend:
* Find files in sub directories
* Find files in other places like project spaces

https://github.com/owncloud/web/pull/6841
https://github.com/owncloud/web/pull/6873
https://github.com/owncloud/web/pull/6887
https://github.com/owncloud/web/pull/6884
