Implement Concurrency9 package #3481

Job	Run time
Prepare CodeQL unit test matrix	4s
Run unit tests (cpp, 2.19.4, codeql-cli/v2.19.4, codeql-bundle-v2.19.4, ubuntu-latest-xl, codeql-...	1h 35m 38s
Run unit tests (c, 2.19.4, codeql-cli/v2.19.4, codeql-bundle-v2.19.4, ubuntu-latest-xl, codeql-cl...	34m 58s
Validate test results	4s
	2h 10m 44s

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