Library products are now cached by the module cache

Static and dynamic library targets can now be cached as binary XCFrameworks alongside framework targets, so projects that depend on libraries can restore those modules from cache instead of rebuilding from source. Generated projects receive correct Swift module paths and public header directories when restoring from a cached library XCFramework. Mixed graphs where some modules are frameworks and others are libraries share the same binary caching pipeline through xcodebuild -create-xcframework -library, with -headers passed when the source target declares public headers.