refactor: add format_max_gas_fee helper for type-safe MaxGasFee seria… #547

Job	Run time
plan	46s
build-local-artifacts (aarch64-apple-darwin)	9m 32s
build-local-artifacts (aarch64-unknown-linux-gnu)	9m 6s
build-local-artifacts (x86_64-apple-darwin)	16m 18s
build-local-artifacts (x86_64-unknown-linux-gnu)	8m 13s
build-global-artifacts	47s
host	1m 1s
announce	3s
	45m 46s

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