[OAuth] Support https localhost redirect uri handling

The pre-existing QOAuthHttpServerReplyHandler supports OAuth 2 redirections for http://localhost:<port>/<path>

However some authorization servers either don't support such redirect uris, or support them only at development-time (but not for published applications).

This item is about adding 'https' capability to the handler by internally using a QSslServer (https://localhost:<port>/<path>).

This solution has its drawback on certificate handling: the user needs to install a locally trusted certificate to avoid the user-agent (browser) from issuing warnings. But with that in mind, there's still likely use cases in a more integrated and controlled environments where this is feasible to do.