Add C `Contracts` package #2721

Job	Run time
Prepare supported CodeQL environment matrix	4s
Run Guideline Recategorization tests	12s
Run release tests	9s
Run analysis report tests (2.18.4, codeql-cli/v2.18.4, codeql-bundle-v2.18.4)	3m 46s
	4m 11s

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