feat: add arbitrum chain methods to `Chain` #425

Job	Run time
feature-checks	1m 3s
clippy	31s
docs	32s
fmt	13s
miri --no-default-features	45s
test stable --no-default-features	20s
miri	45s
wasm	23s
test stable	23s
miri --all-features	1m 6s
test stable --all-features	37s
test beta --no-default-features	24s
test beta	25s
test beta --all-features	35s
test nightly --no-default-features	22s
test nightly	22s
test nightly --all-features	29s
test 1.81 --no-default-features	22s
test 1.81	21s
deny / cargo deny check	14s
	10m 12s

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