Parallel tessellation with opt-in `rayon` feature #9100

Job	Run time
Format + check + test	7m 34s
android	29s
cargo-deny aarch64-apple-darwin	39s
Check Windows	1m 55s
Check wasm32 + wasm-bindgen	2m 23s
cargo-deny aarch64-linux-android	38s
cargo-deny i686-pc-windows-gnu	40s
cargo-deny i686-pc-windows-msvc	39s
cargo-deny i686-unknown-linux-gnu	43s
cargo-deny wasm32-unknown-unknown	42s
cargo-deny x86_64-apple-darwin	43s
cargo-deny x86_64-pc-windows-gnu	42s
cargo-deny x86_64-pc-windows-msvc	38s
cargo-deny x86_64-unknown-linux-gnu	41s
cargo-deny x86_64-unknown-linux-musl	36s
cargo-deny x86_64-unknown-redox	41s
	20m 23s

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