nextcloudclient port

Hi.
This is my first try on porting anything, any help is very much
appreciated.
Test for architectures other than amd64 needed.

Some patches to make it work were needed:
- HTTP/Basic auth by removing QtWebEngine, as it's not available. Patch
similar to [1]
- Work with LibreSSL [2]

[1]https://github.com/nextcloud/desktop/issues/932#issuecomment-485338640
[2]https://github.com/nextcloud/desktop/issues/738#issuecomment-470359183

Best
--
Adriano Barbosa