DocC builds resolve dependency module maps for SwiftPM targets

DocC generation no longer fails on generated Tuist projects for Swift Package targets whose public Objective-C headers import another module from the same package without a declared target dependency (the Firebase case). Tuist derives the missing target dependency from concrete #import / #include references in public headers and copies the dependency module map to the canonical Modules/module.modulemap location so Clang ExtractAPI can discover it.