[Dependency Scanning] Refactor Swift Scanner loader to be standalone

- 'SwiftModuleScanner' will now be owned directly by the 'ModuleDependencyScanningWorker' and will contain all the necessary custom logic, instead of being instantiated by the module interface loader for each query
- Moves ownership over module output path and sdk module output path directly into the scanning worker, instead of the cache

include/swift/DependencyScan/ModuleDependencyScanner.h

@@ -15,7 +15,7 @@
 #include "swift/AST/Identifier.h"
 #include "swift/AST/ModuleDependencies.h"
 #include "swift/Frontend/ModuleInterfaceLoader.h"
-#include "swift/Serialization/SerializedModuleLoader.h"
+#include "swift/Serialization/ScanningLoaders.h"
 #include "llvm/CAS/CASReference.h"
 #include "llvm/Support/ThreadPool.h"
 
@@ -38,17 +38,14 @@ public:
 private:
   /// Retrieve the module dependencies for the Clang module with the given name.
   ModuleDependencyVector scanFilesystemForClangModuleDependency(
-      Identifier moduleName, StringRef moduleOutputPath,
-      StringRef sdkModuleOutputPath,
+      Identifier moduleName,
       const llvm::DenseSet<clang::tooling::dependencies::ModuleID>
           &alreadySeenModules,
       llvm::PrefixMapper *prefixMapper);
 
   /// Retrieve the module dependencies for the Swift module with the given name.
   ModuleDependencyVector scanFilesystemForSwiftModuleDependency(
-      Identifier moduleName, StringRef moduleOutputPath,
-      StringRef sdkModuleOutputPath, llvm::PrefixMapper *prefixMapper,
-      bool isTestableImport = false);
+      Identifier moduleName, bool isTestableImport = false);
 
   /// Query dependency information for header dependencies
   /// of a binary Swift module.
@@ -90,7 +87,7 @@ private:
   // The Clang scanner tool used by this worker.
   clang::tooling::dependencies::DependencyScanningTool clangScanningTool;
   // Swift and Clang module loaders acting as scanners.
-  std::unique_ptr<ModuleInterfaceLoader> swiftScannerModuleLoader;
+  std::unique_ptr<SwiftModuleScanner> swiftModuleScannerLoader;
 
   // Base command line invocation for clang scanner queries (both module and header)
   std::vector<std::string> clangScanningBaseCommandLineArgs;
@@ -102,6 +99,11 @@ private:
   // Working directory for clang module lookup queries
   std::string clangScanningWorkingDirectoryPath;
 
+  /// The location of where the explicitly-built modules will be output to
+  std::string moduleOutputPath;
+  /// The location of where the explicitly-built SDK modules will be output to
+  std::string sdkModuleOutputPath;
+
   // CAS instance.
   std::shared_ptr<llvm::cas::ObjectStore> CAS;
   std::shared_ptr<llvm::cas::ActionCache> ActionCache;