[python] Add missing tests on resolving forward references from new-style type alias

GitOrigin-RevId: ab9b688a7463b61ca262ec679781fb314ed74e8e

python/testData/resolve/ClassLevelNewStyleTypeAliasForwardReference.py

@@ -0,0 +1,6 @@
+class C:
+    type Alias = list[MyClass]
+    #                    <ref>
+
+class MyClass:
+    pass

python/testData/resolve/TopLevelNewStyleTypeAliasForwardReference.py

@@ -0,0 +1,5 @@
+type Alias = list[MyClass]
+#                    <ref>
+
+class MyClass:
+    pass