Support Serde attributes #2240

Job	Run time
maybe-expedite	3s
lint	4m 1s
test (third-party, bincode, stable)	11m 39s
test (third-party, bincode, nightly)	10m 51s
test (third-party, postcard, stable)	13m 32s
test (third-party, postcard, nightly)	15m 20s
test (other, bincode, stable)	24m 7s
test (other, bincode, nightly)	32m 55s
test (other, postcard, stable)	26m 24s
test (other, postcard, nightly)	33m 15s
all-checks	1s
	2h 52m 8s

Provide feedback