feat: Expressify `str.slice` #5481

Job	Run time
check-features	6m 59s
check-wasm	4m 28s
integration-test (ubuntu-latest)	1m 48s
test (ubuntu-latest)	8m 33s
test (windows-latest)	8m 30s
integration-test (windows-latest)	3m 27s
	33m 45s

Provide feedback