[FR] WebDAV: Add `PROPFIND` HTTP method

[pataquets]

RFC: https://datatracker.ietf.org/doc/html/rfc4918#section-9

As of now, the PROPFIND method is not recognized as a valid method.
I guess that just "whitelisting" it and handling it like a GET method would do.

[pataquets]

Looked easy enough, I gave it a stab at #301.