Prototype for `jj api` #10788

Job	Run time
Check protos	50s
build (ubuntu-latest)	4m 48s
build (macos-14)	3m 18s
build (windows-latest)	8m 57s
build (ubuntu-latest, --all-features)	5m 39s
cargo-deny (advisories)	27s
cargo-deny (bans licenses sources)	25s
Clippy check	1m 44s
Check that MkDocs can build the docs	28s
Check that MkDocs can build the docs with Poetry 1.3.2	41s
Check formatting	14s
	27m 31s

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