Support for DAV requests

[dagwieers]

It would be useful to have support for the following WebDAV HTTP methods (RFC4918):

• COPY, LOCK, MKCOL, MOVE, PROPFIND, PROPPATCH, UNLOCK

Some interfaces require WebDAV support (e.g. NextCloud API).
https://docs.nextcloud.com/server/15/developer_manual/client_apis/WebDAV/basic.html?highlight=mkcol