Use cache for DictExpr as well (#19536)

Fixes #14271
Fixes #14636

TBH examples in those issues are already sufficiently fast (probably
because of combined effect of fast dict literals, and the fact that
there are some lists and/or function calls in that examples, so some
caching already kicks in). But this PR will probably make them even
faster.

This has ~0 effect on self-check.

Author: ilevkivskyi

mypy/checkexpr.py

@@ -6043,7 +6043,7 @@ def accept(
             # We cannot use cache inside lambdas, because they skip immediate type
             # context, and use enclosing one, see infer_lambda_type_using_context().
             # TODO: consider using cache for more expression kinds.
-            elif isinstance(node, (CallExpr, ListExpr, TupleExpr, OpExpr)) and not (
+            elif isinstance(node, (CallExpr, ListExpr, TupleExpr, DictExpr, OpExpr)) and not (
                 self.in_lambda_expr or self.chk.current_node_deferred
             ):
                 if (node, type_context) in self.expr_cache: