PY-71002 PEP-696: Adapt the interfaces and implementations of Type Parameter types for the support of defaults

In particular:
- Add getters and setters for default types of Type Parameters
- Change the type of declaration elements for Type Parameters from hardcoded PyTargetExpression to PyQualifiedNameOwner to make it possible to set new-style Type Parameters as declaration elements
- Correctly calculate the qualified names of the new-style type alias statements as now they will be used in declaration elements of Type Parameters

GitOrigin-RevId: 5185d85c1a75052dfcb3f97c0eee17b52540d24b

python/python-psi-api/src/com/jetbrains/python/psi/PyTypeParameter.java

@@ -11,7 +11,7 @@ import org.jetbrains.annotations.Nullable;
  * Represents a Type Parameter that can be a part of {@link PyTypeParameterList}<br>
  * For more information see <a href="https://peps.python.org/pep-0695/">PEP 695</a>
  */
-public interface PyTypeParameter extends PyAstTypeParameter, PyElement, PsiNameIdentifierOwner, PyTypedElement, StubBasedPsiElement<PyTypeParameterStub> {
+public interface PyTypeParameter extends PyAstTypeParameter, PyElement, PsiNameIdentifierOwner, PyTypedElement, PyQualifiedNameOwner, StubBasedPsiElement<PyTypeParameterStub> {
 
   @Override
   @Nullable

python/python-psi-api/src/com/jetbrains/python/psi/types/PyTypeParameterType.java

@@ -79,4 +79,9 @@ public interface PyTypeParameterType extends PyType {
    * Results of {@code getScopeOwner()} and {@link #getName()} constitute unique "coordinates" of a given type parameter.
    */
   @Nullable PyQualifiedNameOwner getScopeOwner();
+
+  @Nullable
+  default PyType getDefaultType() {
+    return null;
+  }
 }