Fixed #29545 -- Fixed using filter lookups againts nested subquery expressions.

Made sql.Where resolve lhs of its child nodes. This is necessary to
allow filter lookups against nested subquery expressions to properly
resolve their OuterRefs to Cols.

Thanks Oskar Persson for the simplified test case.

tests/lookup/tests.py

@@ -942,3 +942,17 @@ class LookupTests(TestCase):
             pk_exists=Exists(qs),
         )
         self.assertCountEqual(seasons, Season.objects.all())
+
+    def test_nested_outerref_lhs(self):
+        tag = Tag.objects.create(name=self.au1.alias)
+        tag.articles.add(self.a1)
+        qs = Tag.objects.annotate(
+            has_author_alias_match=Exists(
+                Article.objects.annotate(
+                    author_exists=Exists(
+                        Author.objects.filter(alias=OuterRef(OuterRef('name')))
+                    ),
+                ).filter(author_exists=True)
+            ),
+        )
+        self.assertEqual(qs.get(has_author_alias_match=True), tag)