SwiftPM prebuilt paths are sanitized for packages like SwiftSyntax

Paths decoded out of workspace-state.json are sanitized before they are converted to AbsolutePath or RelativePath, with the same /private/var normalization that already applied to dependency, artifact, checkout, and include paths. Precompiled SwiftSyntax packages whose archives carry odd control characters used to crash during project generation. The prebuilt library directory is also added to LD_RUNPATH_SEARCH_PATHS so macro executables find Swift compatibility dylibs (e.g. libswiftCompatibilitySpan.dylib) at runtime.