feat(syn-solidity): add statements and expressions #706

Job	Run time
feature checks	3m 3s
docs	53s
clippy	1m 8s
fmt	21s
check WASM	34s
test stable --no-default-features	1m 12s
test stable	1m 22s
test stable --all-features	2m 24s
test beta --no-default-features	54s
test beta	56s
test beta --all-features	1m 8s
test nightly --no-default-features	1m 26s
test nightly	1m 36s
test nightly --all-features	1m 48s
test 1.65 --no-default-features	2m 33s
test 1.65	2m 1s
test 1.65 --all-features	2m 2s
	25m 21s

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