Package documentation module imports supported (DocC)

DocC builds for generated Tuist projects succeed on Swift package targets whose public Objective-C headers import another module from the same package, even when the manifest does not declare that dependency (the Firebase pattern). Tuist now derives the missing target dependency from concrete #import / #include references in public headers, only when the imported module matches a regular target in the same package, only when it is not already declared, and only when adding it would not create a cycle. For framework targets, the canonical Modules/module.modulemap is copied post-build so Clang’s ExtractAPI can resolve dependency module maps during DocC.