[clang] [clang] Add diagnostic for friend declaration of closure type member (PR #191419)

[Corentin Jabot via cfe-commits]

================
@@ -12245,7 +12245,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td>[<a href="https://wg21.link/expr.prim.lambda.closure">expr.prim.lambda.closure</a>]</td>
     <td>CD4</td>
     <td>Explicit instantiation/specialization of generic lambda <TT>operator()</TT></td>
-    <td class="unknown" align="center">Unknown</td>
+    <td class="unreleased" align="center">Clang 22</td>
----------------
cor3ntin wrote:

```suggestion
    <td class="unreleased" align="center">Clang 23</td>
```

https://github.com/llvm/llvm-project/pull/191419