MINOR: h3: implement graceful shutdown with GOAWAY

Implement graceful shutdown as specified in RFC 9114. A GOAWAY frame is
generated with stream ID to indicate range of processed requests.

This process is done via the release app protocol operation. The MUX
is responsible to emit the generated GOAWAY frame after app release. A
CONNECTION_CLOSE will be emitted once there is no unacknowledged STREAM
frames.
1 file changed