Fix arbitrary namespace in PROPFIND

[PVince81]

Arbitrary namespaces can usually be URLs, so we have to properly
pass them into the formatter instead of concatenating it as an alias.

Also fixed PROPFIND response to not contain empty status blocks.

Discovered while debugging PROPPATCH here: owncloud/ocis-reva#57 (comment)

Steps to reproduce: use the steps from owncloud/core#32660 against a resource on the API backend (port 9140)

Before this fix, broken namespaces:

<?xml version="1.0" encoding="utf-8"?>
<d:multistatus xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns" xmlns:oc="http://owncloud.org/ns">
<d:response>
   <d:href>/remote.php/webdav/litmus/</d:href>
   <d:propstat>
      <d:prop></d:prop>
      <d:status>HTTP/1.1 200 OK</d:status>
   </d:propstat>
   <d:propstat>
      <d:prop>
         <http://example.com/alpha:somename></http://example.com/alpha:somename>
         <http://example.com/beta:somename></http://example.com/beta:somename>
         <http://example.com/gamma:somename></http://example.com/gamma:somename>
         <http://example.com/delta:somename></http://example.com/delta:somename>
         <http://example.com/epsilon:somename></http://example.com/epsilon:somename>
         <http://example.com/zeta:somename></http://example.com/zeta:somename>
         <http://example.com/eta:somename></http://example.com/eta:somename>
         <http://example.com/theta:somename></http://example.com/theta:somename>
         <http://example.com/iota:somename></http://example.com/iota:somename>
         <http://example.com/kappa:somename></http://example.com/kappa:somename>
   </d:prop>
   <d:status>HTTP/1.1 404 Not Found</d:status>
   </d:propstat>
</d:response>
</d:multistatus>

After this fix:

<?xml version="1.0" encoding="utf-8"?>
<d:multistatus xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns" xmlns:oc="http://owncloud.org/ns">
  <d:response>
    <d:href>/remote.php/webdav/litmus/</d:href>
    <d:propstat>
      <d:prop>
        <somename xmlns="http://example.com/alpha"/>
        <somename xmlns="http://example.com/beta"/>
        <somename xmlns="http://example.com/gamma"/>
        <somename xmlns="http://example.com/delta"/>
        <somename xmlns="http://example.com/epsilon"/>
        <somename xmlns="http://example.com/zeta"/>
        <somename xmlns="http://example.com/eta"/>
        <somename xmlns="http://example.com/theta"/>
        <somename xmlns="http://example.com/iota"/>
        <somename xmlns="http://example.com/kappa"/>
      </d:prop>
      <d:status>HTTP/1.1 404 Not Found</d:status>
    </d:propstat>
  </d:response>
</d:multistatus>

Note: I don't think this will fix litmus tests as it expects custom properties to be settable while here they are returned as 404. Still, it's a step forward to at least make the response properly parse-able.

@butonic

[labkode]

Thanks @PVince81, the CS3APIs allow for arbitrary metadata, should be possible to map PATCH to SetArbitraryMetadata calls.

[PVince81]

the CS3APIs allow for arbitrary metadata, should be possible to map PATCH to SetArbitraryMetadata calls.

I think the trick is to define a proper format/convention for the key string in arbitrary metadata, to not conflict with the built-in ones.