feat: add ssz support for beacon request types #3330

Job	Run time
clippy	1m 11s
doctest	3m 29s
cfg-check	1m 17s
docs	2m 2s
feature-checks	7m 29s
fmt	11s
no-std	34s
test ubuntu-latest stable --no-default-features	2m 48s
wasm-unknown	2m 24s
wasm-wasi	3m 28s
test ubuntu-latest stable	2m 38s
test ubuntu-latest nightly --no-default-features	2m 47s
test ubuntu-latest nightly	2m 41s
test ubuntu-latest 1.76 --no-default-features	1m 51s
test ubuntu-latest 1.76	2m 2s
test windows-latest stable --no-default-features	7m 34s
test windows-latest stable	7m 31s
test windows-latest nightly --no-default-features	7m 4s
test windows-latest nightly	6m 49s
test windows-latest 1.76 --no-default-features	5m 11s
test windows-latest 1.76	6m 12s
	1h 17m 13s

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