[clang] [clang][Parser] "Better" error messages for invalid template template (PR #95726)

[Vlad Serebrennikov via cfe-commits]

================
@@ -1145,8 +1145,10 @@ namespace cwg181 { // cwg181: yes
   namespace X {
     template <template X<class T> > struct A { };
     // expected-error at -1 +{{}}
+    //  expected-note at -2 {{did you mean to use 'typename'?}}
----------------
Endilll wrote:

```suggestion
    //   expected-note at -2 {{did you mean to use 'typename'?}}
```

https://github.com/llvm/llvm-project/pull/95726