[clang] clang-format: Add "AllowShortNamespacesOnASingleLine" option (PR #105597)

[Owen Pan via cfe-commits]

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@@ -972,6 +972,11 @@ struct FormatStyle {
   /// \version 3.7
   bool AllowShortLoopsOnASingleLine;
 
+  /// If ``true``, ``namespace a { class b; }`` can be put on a single a single
+  /// line.
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owenca wrote:

```suggestion
  /// If ``true``, ``namespace a { class b; }`` can be put on a single line.
```

https://github.com/llvm/llvm-project/pull/105597