rune: Move tests around and Send + Sync #1854

Job	Run time
rustfmt	9s
clippy	2m 13s
docs	3m 24s
msrv	1m 32s
nightly	3m 33s
basics	1s
no_std (ubuntu-latest, minimal)	1m 5s
build_feature (alloc)	3m 27s
no_std (macos-latest, minimal)	1m 12s
test_lib	4m 19s
build_feature (cli)	3m 56s
test_doc	6m 18s
build_feature (cli,doc)	4m 9s
build_feature (cli,fmt)	4m 4s
test_miri (rune)	3m 35s
test_rune	3m 16s
wasm	1m 11s
build_feature (doc)	3m 50s
test_miri (rune-core)	42s
build_feature (workspace)	3m 27s
test_miri (rune-alloc)	6m 3s
build_feature (languageserver)	3m 50s
build_feature (byte-code)	3m 29s
build_feature (capture-io)	3m 36s
build_feature (emit)	3m 30s
	1h 15m 51s

Provide feedback