[clang] [clang-format] Support BraceWrapping.AfterNamespace with AllowShortNamespacesOnASingleLine (PR #123010)

[Owen Pan via cfe-commits]

================
@@ -367,8 +367,12 @@ class LineJoiner {
 
     if (Style.AllowShortNamespacesOnASingleLine &&
         TheLine->First->is(tok::kw_namespace) &&
-        TheLine->Last->is(tok::l_brace)) {
-      const auto result = tryMergeNamespace(I, E, Limit);
+        ((Style.BraceWrapping.AfterNamespace &&
+          NextLine.First->is(tok::l_brace)) ||
+         (!Style.BraceWrapping.AfterNamespace &&
+          TheLine->Last->is(tok::l_brace)))) {
+      const auto result =
+          tryMergeNamespace(I, E, Limit, Style.BraceWrapping.AfterNamespace);
----------------
owenca wrote:

```suggestion
        TheLine->First->is(tok::kw_namespace)) {
      const auto result = tryMergeNamespace(I, E, Limit);
```

https://github.com/llvm/llvm-project/pull/123010