Android: Introduce HTTP headers to MediaPlayer

Added using the headers from QNetworkRequest to be sent together with the request
for the data in MediaPlayer::setDataSource.

The MediaPlayer requires also a Context object, together with headers,
to resolve the Uri. It will try to find a content provider.
Since no content providers are implemented, this produces a warning:
"MediaPlayer: Couldn't open file on client side; trying server side: java.io.FileNotFoundException: No content provider"

Task-number: QTBUG-74073
Change-Id: I1566953b523e84400882ba9d3a968cec6b4a61cf
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>