Support Serde attributes #2236

Job	Run time
maybe-expedite	3s
lint	4m 12s
test (third-party, bincode, stable)	11m 48s
test (third-party, bincode, nightly)	10m 16s
test (third-party, postcard, stable)	12m 9s
test (third-party, postcard, nightly)	10m 38s
test (other, bincode, stable)	24m 56s
test (other, bincode, nightly)	30m 25s
test (other, postcard, stable)	25m 42s
test (other, postcard, nightly)	32m 2s
all-checks	1s
	2h 42m 12s

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