[clang] clang-format: Add IncludeSortKey option (PR #137840)

[Björn Schäpers via cfe-commits]

================
@@ -166,6 +166,16 @@ struct IncludeStyle {
   /// directives that use the specified character are considered.
   /// \version 19
   MainIncludeCharDiscriminator MainIncludeChar;
+
+  enum IncludeSortKeyDiscriminator : int8_t {
----------------
HazardyKnusperkeks wrote:

Can you sort this alphabetically with the other members?

https://github.com/llvm/llvm-project/pull/137840