cli: add `jj operation show` and `jj operation diff` commands #12718

Job	Run time
build (ubuntu-latest)	4m 14s
build (macos-14)	3m 17s
build (windows-latest)	9m 20s
build (ubuntu-latest, --all-features)	5m 16s
Build jj-lib without Git support	46s
Check protos	27s
cargo-deny (advisories)	24s
cargo-deny (bans licenses sources)	24s
Clippy check	2m 21s
Check that MkDocs can build the docs	22s
Check that MkDocs can build the docs with Poetry 1.8	26s
Check formatting	15s
	27m 32s

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