[6.2 🍒][Dependency Scanning] Consider '-swift-module-file' inputs when looking for dependencies

Previously this flag was only used to pass explicit dependencies to compilation tasks. This change adds support for the dependency scanner to also consider these inputs when resolving dependencies.

Resolves https://github.com/swiftlang/swift-driver/issues/1951

include/swift/AST/ModuleLoader.h

@@ -375,6 +375,7 @@ public:
                         StringRef moduleOutputPath, StringRef sdkModuleOutputPath,
                         const llvm::DenseSet<clang::tooling::dependencies::ModuleID> &alreadySeenClangModules,
                         const std::vector<std::string> &swiftModuleClangCC1CommandLineArgs,
+                        const llvm::StringMap<std::string> &explicitSwiftModuleInputs,
                         InterfaceSubContextDelegate &delegate,
                         llvm::PrefixMapper *mapper = nullptr,
                         bool isTestableImport = false) = 0;