[clang] [clang-format] Add FilesBeforeFolders option to SortIncludes (PR #208954)

[Savvas Shiakas via cfe-commits]

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@@ -6821,6 +6821,19 @@ the configuration (without a prefix: ``Auto``).
        # include "A.inc"              # include "A.h"
        # include "A-util.h"           # include "A.inc"
 
+  * ``bool FilesBeforeFolders`` When ``true``, sort includes so that files in a directory appear
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Shiakaron wrote:

> what does it do when its false? does it leave it alone or is it FoldersBeforeFiles?

The default is `false` which keeps the existing logic intact, i.e. simple alphabetical sorting. When setting to `true` the files are sorted in the proposed way: 
1. sort files in the folder sort alphabetically
2. If there are subfolders:
  a. sort subfolders alphabetically
  b. iterate on each subfolder 

 > How does it work with "" and <>?

They are treated the same, so `<boost/cast.hpp>` would be before `<boost/align/align.hpp>`


https://github.com/llvm/llvm-project/pull/208954