Add `CasePathsCore` module #555

Job	Run time
macOS (Xcode 15.4)	35s
Android	29s
macOS (Xcode 16.2)	33s
Check Macro Compatibility	37s
Ubuntu (Swift 5.10)	19s
macOS Library Evolution (Xcode 15.4)	34s
Wasm	28s
macOS Library Evolution (Xcode 16.2)	36s
	4m 11s

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