When receiving a GOAWAY frame, the client:
* immediately closes the connection if there are no active requests
* refuses to open streams with stream IDs larger than the stream ID in
the GOAWAY frame
* closes the connection once the stream count drops to zero
* http3: reset request streams accepted after graceful shutdown
The server needs to let the client know that these streams
are not getting processed, using the H3_REQUEST_REJECTED
error code.
* add an integration test for graceful shutdown stream cancellations
