[clang] [clang-format] Add options to set number of empty lines after includes (PR #78957)

[Björn Schäpers via cfe-commits]

================
@@ -4831,6 +4848,7 @@ struct FormatStyle {
            DerivePointerAlignment == R.DerivePointerAlignment &&
            DisableFormat == R.DisableFormat &&
            EmptyLineAfterAccessModifier == R.EmptyLineAfterAccessModifier &&
+           EmptyLinesAfterIncludes == R.EmptyLinesAfterIncludes &&
            EmptyLineBeforeAccessModifier == R.EmptyLineBeforeAccessModifier &&
----------------
HazardyKnusperkeks wrote:

```suggestion
           EmptyLineBeforeAccessModifier == R.EmptyLineBeforeAccessModifier &&
           EmptyLinesAfterIncludes == R.EmptyLinesAfterIncludes &&
```

https://github.com/llvm/llvm-project/pull/78957