PY-16412 Properly import named tuples for their use in type hints

For that I introduced a new method -- getElement() in PyType
that allows to find out the element that can be used to reference
this type according to PEP 484 perspective, e.g. a target assignment
for TypeVar's and NamedTuples and PSI class themselves for class types.

Also, class object types for named tuples are wrapped in typing.Type[]
as expected.

python/testSrc/com/jetbrains/python/intentions/PyAnnotateVariableTypeIntentionTest.java

@@ -231,6 +231,26 @@ public class PyAnnotateVariableTypeIntentionTest extends PyIntentionTestCase {
     doAnnotationTest();
   }
 
+  public void testAnnotationTypingNamedTupleInOtherFile() {
+    doMultiFileAnnotationTest();
+  }
+
+  public void testAnnotationTypingNamedTupleClassInOtherFile() {
+    doMultiFileAnnotationTest();
+  }
+
+  public void testAnnotationTypingNamedTupleDirectInheritorInOtherFile() {
+    doMultiFileAnnotationTest();
+  }
+
+  public void testAnnotationCollectionsNamedTupleInOtherFile() {
+    doMultiFileAnnotationTest();
+  }
+
+  public void testAnnotationCollectionsNamedTupleClassInOtherFile() {
+    doMultiFileAnnotationTest();
+  }
+
   public void testConflictWithAnnotationFunctionTypeIntention() {
     doTest(LanguageLevel.PYTHON36);
   }