Add `Serialize` and `Deserialize` traits to `Collateral` #819

Job	Run time
lint	12s
deny (advisories)	1m 56s
deny (bans licenses sources)	2m 15s
doc (stable)	1m 59s
doc (beta)	1m 23s
build (stable)	1m 58s
build (beta)	2m 26s
build (nightly-2022-12-13)	2m 9s
clippy (stable)	1m 57s
clippy (beta)	1m 9s
sort	46s
test (stable)	4m 41s
test (beta)	4m 51s
test (nightly-2022-12-13)	4m 54s
build-no-alloc (thumbv6m-none-eabi)	1m 47s
build-no-alloc (thumbv7m-none-eabi)	1m 55s
build-no-alloc (thumbv8m.main-none-eabi)	2m 35s
build-no-alloc (aarch64-linux-android)	1m 49s
build-no-alloc (aarch64-apple-ios)	2m 22s
coverage	2m 32s
notify	2s
	45m 38s

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