SwiftPM prebuilt paths no longer break generation

Paths decoded from SwiftPM workspace-state.json for prebuilt products are now sanitized to drop control characters and normalize /private/var variants before they reach Tuist. Prebuilt library directories are also added to LD_RUNPATH_SEARCH_PATHS so macro executables can locate back-deployed Swift compatibility dylibs such as libswiftCompatibilitySpan.dylib at runtime. Precompiled SwiftSyntax-based packages and local Swift macros now generate and link reliably.