Update examples CI to use swift-test-matrix #167

Job	Run time
Construct Examples matrix	5s
Benchmarks / Construct Benchmarks matrix	5s
Cxx interop / Construct Cxx interop matrix	3s
Soundness / Check generated code	1m 12s
Soundness / Swift license headers check	6s
Unit tests / Construct unit test matrix	5s
Soundness / Documentation check	1m 21s
Soundness / API breakage check	1m 11s
Soundness / Broken symlinks check	3s
Soundness / Format check	38s
Soundness / License headers check	2s
Soundness / Python lint check	7s
Soundness / Shell check	35s
Soundness / Unacceptable language check	5s
Soundness / YAML lint check	3s
Cxx interop / Cxx interop / Linux (6.0)	58s
Cxx interop / Cxx interop / Linux (nightly-6.1)	1m 6s
Cxx interop / Cxx interop / Linux (nightly-main)	1m 11s
Examples / Linux (6.0)	7m 39s
Examples / Linux (nightly-6.1)	2m 54s
Examples / Linux (nightly-main)	2m 59s
Benchmarks / Benchmarks / Linux (6.0)	2m 39s
Benchmarks / Benchmarks / Linux (nightly-6.1)	2m 58s
Benchmarks / Benchmarks / Linux (nightly-main)	2m 54s
Unit tests / Unit tests / Linux (6.0)	1m 26s
Unit tests / Unit tests / Linux (nightly-6.1)	1m 37s
Unit tests / Unit tests / Linux (nightly-main)	1m 47s
	35m 49s

Provide feedback