Add fileid and etag to MKCOL webdav response

We may need to add something like:
```
w.Header().Set(HeaderOCFileID, resourceid.OwnCloudResourceIDWrap(newInfo.Id))
w.Header().Set(HeaderOCETag, newInfo.Etag)
```
To internal/http/services/owncloud/ocdav/mkcol.go in order to "comply" to Reva edge as in #4767

This would require some other change in order to avoid an extra `Stat` call