Add CI support for doc tests. #1756

Job	Run time
cargo check (msrv) (wasm32)	38s
cargo check (msrv) (windows-latest)	1m 33s
cargo clippy (windows-latest)	2m 17s
cargo check (msrv) (macos-latest)	39s
cargo check (aarch64-android)	29s
cargo clippy (macos-latest)	1m 29s
cargo check (msrv) (ubuntu-latest)	40s
cargo clippy (wasm32)	1m 23s
cargo clippy (ubuntu-latest)	1m 43s
cargo doc	1m 40s
formatting	22s
Prime LFS Cache	7s
cargo test (wasm32)	30s
typos	4s
cargo test (windows-latest)	2m 38s
cargo test (macos-latest)	1m 51s
cargo test (ubuntu-latest)	3m 43s
	21m 46s

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