feat: port `ethers_core::types::Chain` #3

Job	Run time
wasm	8s
feature-checks	43s
test stable --no-default-features	21s
miri --no-default-features	41s
test stable	9s
miri	32s
clippy	12s
test stable --all-features	27s
docs	17s
miri --all-features	1m 1s
test beta --no-default-features	13s
test beta	17s
fmt	14s
test beta --all-features	14s
test nightly --no-default-features	26s
test nightly	23s
test nightly --all-features	22s
test 1.65 --no-default-features	5m 20s
test 1.65	3m 36s
	15m 36s

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