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

[Björn Schäpers via cfe-commits]

================
@@ -27981,6 +27981,118 @@ TEST_F(FormatTest, BreakBinaryOperations) {
                Style);
 }
 
+TEST_F(FormatTest, ShortNamespacesOption) {
+  FormatStyle Style = getLLVMStyle();
+  Style.AllowShortNamespacesOnASingleLine = true;
+  Style.FixNamespaceComments = false;
+
+  // Basic functionality
----------------
HazardyKnusperkeks wrote:

```suggestion
  // Basic functionality.
```
Comments ending with full stop.

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