[clang] [clang-format]: Add `Custom` to `ShortFunctionStyle`; add new AllowShortFunctionsOnASingleLineOptions for granular setup (PR #134337)

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@@ -611,20 +611,40 @@ TEST(ConfigParseTest, ParsesConfiguration) {
   CHECK_PARSE("AllowShortBlocksOnASingleLine: true",
               AllowShortBlocksOnASingleLine, FormatStyle::SBS_Always);
 
-  Style.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
+  // Style.AllowShortFunctionsOnASingleLine = FormatStyle::SFS_Inline;
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sstwcw wrote:

What is the comment for?

https://github.com/llvm/llvm-project/pull/134337