[clang][dataflow] Add an `operator<<` for `OptionalTypeIdentifier`.

[mboehme]

Summary

When tests fail in UncheckedOptionalAccessModelTest.cpp, this prints the name of the optional type instead of a blob of hex.

[mboehme]

Format code.

[ymandel]

Thank you!

clang/unittests/Analysis/FlowSensitive/UncheckedOptionalAccessModelTest.cpp

static void ReplaceAllOccurrences(std::string &S, const std::string &Pattern,
   }
 }
 
 struct OptionalTypeIdentifier {
   std::string NamespaceName;
   std::string TypeName;
 };
 
+static raw_ostream &operator<<(raw_ostream &OS,
+                               const OptionalTypeIdentifier &TypeId) {
+  OS << TypeId.NamespaceName << "::" << TypeId.TypeName;
+  return OS;
+}
+
 class UncheckedOptionalAccessTest
     : public ::testing::TestWithParam<OptionalTypeIdentifier> {
 protected:
   void ExpectDiagnosticsFor(std::string SourceCode) {
     ExpectDiagnosticsFor(SourceCode, ast_matchers::hasName("target"));
   }
 
   template <typename FuncDeclMatcher>