rune: Move tests around and Send + Sync #1855

Job	Run time
clippy	2m 15s
rustfmt	15s
docs	3m 13s
msrv	1m 35s
nightly	3m 26s
basics	1s
wasm	1m 5s
no_std (ubuntu-latest, minimal)	1m 6s
test_miri (rune)	3m 31s
no_std (macos-latest, minimal)	1m 14s
build_feature (alloc)	3m 20s
test_miri (rune-core)	42s
test_doc	6m 10s
build_feature (cli)	4m 13s
test_miri (rune-alloc)	5m 52s
test_lib	4m 26s
build_feature (cli,doc)	4m 12s
build_feature (cli,fmt)	4m 3s
test_rune	3m 9s
build_feature (doc)	3m 54s
build_feature (workspace)	3m 28s
build_feature (languageserver)	3m 55s
build_feature (byte-code)	3m 25s
build_feature (capture-io)	3m 28s
build_feature (emit)	3m 36s
	1h 15m 34s

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