feat(json-abi): improve `JsonAbi::to_sol` #1182

Job	Run time
clippy	1m 8s
docs	22s
feature-checks	2m 7s
miri --no-default-features	2m 21s
test stable --no-default-features	1m 37s
wasm	24s
miri	2m 30s
test stable	1m 45s
miri --all-features	2m 52s
test stable --all-features	1m 0s
test beta --no-default-features	1m 11s
fmt	18s
test beta	46s
test beta --all-features	53s
test nightly --no-default-features	55s
test nightly	1m 33s
test nightly --all-features	1m 42s
test 1.65 --no-default-features	39s
test 1.65	38s
	24m 41s

Provide feedback