feat(rpc-types-engine): add forkchoice state zero helpers #3721

Job	Run time
cfg-check	29s
docs	57s
clippy	1m 15s
doctest	2m 35s
feature-checks	7m 37s
fmt	11s
no-std	12s
test ubuntu-latest stable --no-default-features	2m 16s
wasm-unknown	2m 43s
wasm-wasi	3m 47s
test ubuntu-latest stable	2m 19s
test ubuntu-latest stable --all-features	2m 52s
test ubuntu-latest nightly --no-default-features	1m 16s
test ubuntu-latest nightly	1m 14s
test ubuntu-latest nightly --all-features	1m 40s
test ubuntu-latest 1.78 --no-default-features	1m 33s
test ubuntu-latest 1.78	1m 32s
test windows-latest stable --no-default-features	4m 51s
test windows-latest stable	6m 15s
test windows-latest stable --all-features	6m 6s
test windows-latest nightly --no-default-features	4m 35s
test windows-latest nightly	4m 22s
test windows-latest nightly --all-features	5m 14s
test windows-latest 1.78 --no-default-features	3m 14s
test windows-latest 1.78	3m 17s
	1h 12m 22s

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