Experiment with a new `Group` container #11619

Job	Run time
Format + check + test	56s
Check wasm32 + wasm-bindgen	3m 8s
android	47s
cargo-deny aarch64-apple-darwin	40s
Check Windows	2m 19s
cargo-deny aarch64-linux-android	40s
cargo-deny i686-pc-windows-gnu	43s
cargo-deny i686-pc-windows-msvc	39s
cargo-deny i686-unknown-linux-gnu	38s
cargo-deny wasm32-unknown-unknown	1m 0s
cargo-deny x86_64-apple-darwin	1m 1s
cargo-deny x86_64-pc-windows-gnu	56s
cargo-deny x86_64-pc-windows-msvc	1m 1s
cargo-deny x86_64-unknown-linux-gnu	39s
cargo-deny x86_64-unknown-linux-musl	41s
cargo-deny x86_64-unknown-redox	1m 4s
	16m 52s

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