PY-21204 Create a new class in host file instead of injected fragment

Additionally, I removed usages of deprecated API in CreateClassQuickFix
and utilize SmartPointer to hold the reference to PSI element.

python/testSrc/com/jetbrains/python/PyQuickFixTest.java

@@ -202,6 +202,11 @@ public class PyQuickFixTest extends PyTestCase {
     doInspectionTest("AddClass.py", PyUnresolvedReferencesInspection.class, "Create class 'Xyzzy'", true, true);
   }
 
+  // PY-21204
+  public void testAddClassFromTypeComment() {
+    doInspectionTest(PyUnresolvedReferencesInspection.class, "Create class 'MyClass'", true, true);
+  }
+
   // PY-1602
   public void testAddFunctionToModule() {
     doInspectionTest(