ci: make workflow to verify samples, list all subdirs #636

Job	Run time
Java tests (swift:6.1.2 jdk:Corretto os:jammy)	8m 47s
Swift tests (swift:6.1.2 jdk:Corretto os:jammy)	4m 40s
verify-samples / construct-samples-matrix	3s
soundness / Unacceptable language check	6s
soundness / Documentation check	40s
soundness / Python lint check	7s
soundness / Shell check	33s
soundness / License headers check	5s
soundness / Broken symlinks check	3s
soundness / YAML lint check	3s
soundness / Format check	0s
soundness / API breakage check	0s
	15m 7s

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