Allow async cli execution (#651) #855

Job	Run time
clippy	5m 4s
runefmt	4m 8s
docs	2m 30s
rustfmt	12s
basics	3s
miri_rune_alloc	10m 7s
miri_rune	15m 59s
msrv	4m 41s
build_feature (capture-io)	1m 46s
build_feature (cli,doc)	2m 31s
no_default_features	1m 44s
no_std_minimal	3m 46s
build_feature (cli,fmt)	2m 48s
wasm	1m 54s
build_feature (cli)	2m 13s
build_feature (workspace)	1m 31s
build_feature (languageserver)	2m 25s
build_feature (byte-code)	1m 34s
test	28m 14s
	1h 33m 10s

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