MEDIUM: h3: send SETTINGS before STREAM frames

Complete qcc_send_stream() function to allow to specify if the stream
should be handled in priority. Internally this will insert the qcs
instance in front of <qcc.send_list> to be able to treat it before other
streams.

This functionality is useful when some QUIC streams should be sent
before others. Most notably, this is used to guarantee that H3 SETTINGS
is done first via the control stream.

This must be backported up to 2.7.
3 files changed