rdp: Add initial support for autodetecting network characteristics

Add support for autodetecting network characteristics using the
previously implemented class.
When the graphics pipeline is being used, add the graphics pipeline as
RTT consumer to ensure a smooth experience even on high latencies.
When the SuppressOutput PDU is received, there won't be any reason to
emit RTTRequests, as no frame updates will happen.
In that case, remove the graphics pipeline as RTT consumer, until the
SuppressOutput PDU allows gnome-remote-desktop to send frame updates
again.