Implement package expressions2 #4191

Job	Run time
Prepare CodeQL unit test matrix	4s
Run unit tests (cpp, 2.21.4, codeql-cli/v2.21.4, codeql-bundle-v2.21.4, ubuntu-latest-xl, codeql-...	1h 52m 53s
Run unit tests (c, 2.21.4, codeql-cli/v2.21.4, codeql-bundle-v2.21.4, ubuntu-latest-xl, codeql-cl...	40m 36s
Validate test results	11s
	2h 33m 44s

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