[Dependency Scanning] Add a binary serialization format for the Inter-Module Dependencies Cache

- Adds serialization format based on the LLVM Bitcode File Format (https://llvm.org/docs/BitCodeFormat.html).
- Adds Serialization and Deserialization code.

lib/Serialization/ModuleDependencyScanner.cpp

@@ -124,7 +124,7 @@ ErrorOr<ModuleDependencies> ModuleDependencyScanner::scanInterfaceFile(
     std::string InPath = moduleInterfacePath.str();
     auto compiledCandidates = getCompiledCandidates(Ctx, moduleName.str(),
                                                     InPath);
-    Result = ModuleDependencies::forSwiftInterface(InPath,
+    Result = ModuleDependencies::forSwiftTextualModule(InPath,
                                                    compiledCandidates,
                                                    Args,
                                                    PCMArgs,