Allow searching for favorites

[icewind1991]

Using

<d:eq>
     <d:prop>
          <oc:favorite/>
     </d:prop>
     <d:literal>yes</d:literal>
</d:eq>

As part of the search query

[mention-bot]

@icewind1991, thanks for your PR! By analyzing the history of the files in this pull request, we identified @FlorinPeter, @butonic and @nickvergessen to be potential reviewers.

[MorrisJobke]

@mario Is this the only change needed for the android app or is there more to come?

[mario]

@MorrisJobke I won't know until I start working on "Recently modified" and stuff like that. But maybe I can workaround it for now and not require more server changes...

[mario]

👍 - works as advertised.

[mario]

@icewind1991 two more questions/requests:

1. Searching for shared files/folders
2. Searching by date created (uploaded?) if creationdate is the right attribute?

Would appreciate it, otherwise I have to do propfind and do it manually...

[mario]

@nickvergessen told me that creationdate isn't the right thing for no. 2 requirement. Please link me up when you get the time to relevant issue.

I still need both somehow implemented though.

[mario]

1. So to clarify my first requirement:

All files shared by you, with you, and by link, in a single flat list.

[MorrisJobke]

Tested and works 👍

[MorrisJobke]

@mario Please open separate issues for your requests. And is this now all for the search feature? Or is there still something missing on the server side?

[mario]

@MorrisJobke I opened three relevant issues, and we'll see if it can be achieved using existing implementation or not.