New codec/descriptor protocol work #554

Job	Run time
Generate matrix	3s
linux / test-fast / rust=default	6m 25s
linux / check / rust=stable	1m 57s
linux / check / rust=beta	2m 0s
linux / check / rust=default	5m 22s
macos / check / rust=stable	1m 51s
macos / test / rust=stable	4m 47s
linux / build-minimal / rust=default	1m 24s
windows / check / rust=stable	18m 31s
linux / test / rust=stable	5m 54s
linux / test-fast / rust=beta	5m 9s
windows / test-fast / rust=stable	6m 51s
	1h 0m 14s

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