Cache static and dynamic library targets in the module cache

The module cache now treats static and dynamic library targets as cacheable binary products. Cache warm creates library XCFrameworks via xcodebuild -create-xcframework -library (passing -headers when the source target declares public headers), and on restore generated projects expose cached library Swift module directories and public header directories, so consumers can compile against them. Mixed framework/library graphs can reuse cached binaries across local and CI builds without forcing libraries to become frameworks.