* send goaway when server is shutting down
* http3: track next stream ID instead of last stream ID for GOAWAYs
* refactor the graceful shutdown integration tests
* http3: improve GOAWAY frame parsing tests
* http3: simplify server graceful shutdown logic
* http3: simplify parsing of GOAWAY frames
* http3: clean up initialization of server contexts
* http3: fix race condition in graceful shutdown logic
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Co-authored-by: WeidiDeng <weidi_deng@icloud.com>
When a stream is reset, we might not have received the frame / stream
type yet. The callback might be able to identify if it was a stream
intended for that application by analyzing the stream reset error.
