Fixed #27595 -- Made ForeignKey.get_col() follow target chains.

Previously, foreign relationships were followed only one level deep which
prevents foreign keys to foreign keys from being resolved appropriately.
This was causing issues such as improper database value conversion for
UUIDField on SQLite because the resolved expression's output field's
internal type wasn't correct. Added tests to make sure unlikely foreign
reference cycles don't cause recursion errors.

Refs #24343.

Thanks oyooyo for the report and Wayne Merry for the investigation.

tests/model_fields/test_uuid.py

@@ -170,8 +170,12 @@ class TestAsPrimaryKey(TestCase):
         self.assertEqual(r.uuid_fk, u2)
 
     def test_two_level_foreign_keys(self):
+        gc = UUIDGrandchild()
         # exercises ForeignKey.get_db_prep_value()
-        UUIDGrandchild().save()
+        gc.save()
+        self.assertIsInstance(gc.uuidchild_ptr_id, uuid.UUID)
+        gc.refresh_from_db()
+        self.assertIsInstance(gc.uuidchild_ptr_id, uuid.UUID)
 
 
 class TestAsPrimaryKeyTransactionTests(TransactionTestCase):