[clang] [clang-format] Add SpaceAfterOperatorKeyword option (PR #137610)

[Owen Pan via cfe-commits]

================
@@ -4463,6 +4463,14 @@ struct FormatStyle {
   /// \version 9
   bool SpaceAfterLogicalNot;
 
+  /// If \c true, a space will be inserted after the ``operator`` keyword.
+  /// \code
+  ///    true:                                false:
+  ///    bool operator == (int a)     vs.     bool operator== (int a)
----------------
owenca wrote:

```suggestion
  ///    bool operator ==(int a);     vs.     bool operator==(int a);
```

https://github.com/llvm/llvm-project/pull/137610