Fix more ser/deser and add tests #370

Job	Run time
linting	1m 47s
mavlink-dump	1m 9s
internal-tests (ardupilotmega)	1m 13s
internal-tests (asluav)	1m 26s
msrv	5m 59s
internal-tests (matrixpilot)	1m 38s
formatting	17s
internal-tests (minimal)	1m 17s
internal-tests (paparazzi)	1m 24s
internal-tests (python_array_test)	1m 27s
internal-tests (slugs)	1m 10s
internal-tests (standard)	1m 10s
internal-tests (test)	1m 11s
internal-tests (ualberta)	1m 25s
internal-tests (uavionix)	1m 16s
internal-tests (icarous)	1m 15s
internal-tests (common)	1m 11s
docs	58s
build	0s
test-embedded-size	0s
	27m 13s

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