Add "Baseline" query suites for C/C++. #3883

Job	Run time
Prepare CodeQL unit test matrix	6s
Run unit tests (cpp, 2.20.7, codeql-cli/v2.20.7, codeql-bundle-v2.20.7, ubuntu-latest-xl, codeql-...	1h 40m 34s
Run unit tests (c, 2.20.7, codeql-cli/v2.20.7, codeql-bundle-v2.20.7, ubuntu-latest-xl, codeql-cl...	35m 12s
Validate test results	4s
	2h 15m 56s

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