H3 interop fixes

[stammw]

Fixes needed to get better results at interop, along with some tooling and tracing.

[djc]

LGTM (pending test fixes).

[github-actions]

Pull Request Test Coverage Report for Build 0fc01a5a2dcbe3eac675fdd5a7b271b848b47237-PR-570

• 16 of 56 (28.57%) changed or added relevant lines in 8 files are covered.
• 7 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.05%) to 70.599%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
quinn-h3/src/body.rs	0	1	0.0%
quinn-h3/src/proto/headers.rs	3	4	75.0%
quinn-h3/src/client.rs	0	3	0.0%
quinn-h3/src/streams.rs	0	3	0.0%
quinn-h3/src/connection.rs	0	4	0.0%
quinn-h3/src/proto/connection.rs	3	9	33.33%
quinn-h3/src/proto/mod.rs	0	8	0.0%
quinn-h3/src/proto/frame.rs	10	24	41.67%

Files with Coverage Reduction	New Missed Lines	%
quinn-h3/src/streams.rs	1	0.0%
quinn-proto/src/packet.rs	1	86.23%
quinn-h3/src/qpack/encoder.rs	5	92.05%

Totals
Change from base Build f078ca955bf560ad464f46824849ac4fdbf7b1f9:	-0.05%
Covered Lines:	9989
Relevant Lines:	14149

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💛 - Coveralls

[stammw]

I think this is ready now.