Switch to generating completions at runtime #2666

Job	Run time
Rustfmt and clippy	51s
Test (x86_64-unknown-linux-gnu, ubuntu-latest, --features=native-tls)	49s
Test (x86_64-unknown-linux-gnu, ubuntu-latest, --no-default-features --features=native-tls,online...	55s
Test (x86_64-apple-darwin, macos-13, --features=native-tls)	2m 21s
Test (aarch64-apple-darwin, macos-14, --features=native-tls)	1m 15s
Test (x86_64-pc-windows-msvc, windows-latest, --features=native-tls)	2m 45s
Test (x86_64-unknown-linux-musl, ubuntu-latest, true)	1m 39s
Test (aarch64-unknown-linux-musl, ubuntu-latest, true, -- --test-threads=4)	15m 13s
Test (arm-unknown-linux-gnueabihf, ubuntu-latest, true, -- --test-threads=4)	2m 20s
	28m 8s

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