MEDIUM: mux-quic: implement RESET_STREAM emission

MEDIUM: mux-quic: implement RESET_STREAM emission

Implement functions to be able to reset a stream via RESET_STREAM.

If needed, a qcs instance is flagged with QC_SF_TO_RESET to schedule a
stream reset. This will interrupt all future send operations.

On stream emission, if a stream is flagged with QC_SF_TO_RESET, a
RESET_STREAM frame is generated and emitted to the transport layer. If
this operation succeeds, the stream is locally closed. If upper layer is
instantiated, error flag is set on it.