Add a dev-tool subpackage #155

Job	Run time
Soundness / Check generated code	1m 10s
Benchmarks / Construct Benchmarks matrix	3s
Soundness / Swift license headers check	8s
Cxx interop / Construct Cxx interop matrix	5s
Unit tests / Construct unit test matrix	3s
Examples / Linux (5.9)	15s
Examples / Windows (6.0)	2s
Examples / Windows (nightly-6.0)	1s
Examples / Linux (5.10)	15s
Examples / Linux (6.0)	16s
Examples / Windows (nightly-main)	3s
Examples / Linux (nightly-6.0)	16s
Soundness / API breakage check	12s
Examples / Linux (nightly-main)	13s
Soundness / Documentation check	14s
Soundness / Broken symlinks check	2s
Soundness / Format check	12s
Soundness / License headers check	3s
Soundness / Shell check	14s
Soundness / Unacceptable language check	2s
Soundness / Python lint check	6s
Soundness / YAML lint check	5s
Unit tests / Unit tests / Linux (6.0)	29s
Unit tests / Unit tests / Linux (nightly-6.0)	30s
Unit tests / Unit tests / Linux (nightly-main)	30s
Benchmarks / Benchmarks / Linux (6.0)	26s
Benchmarks / Benchmarks / Linux (nightly-6.0)	31s
Benchmarks / Benchmarks / Linux (nightly-main)	30s
Cxx interop / Cxx interop / Linux (6.0)	29s
Cxx interop / Cxx interop / Linux (nightly-6.0)	28s
Cxx interop / Cxx interop / Linux (nightly-main)	30s
	8m 23s

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