[clang] [Metal][HLSL] Add support for dumping reflection (PR #181258)

[Finn Plummer via cfe-commits]

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@@ -9735,6 +9726,8 @@ def dxc_no_stdinc : DXCFlag<"hlsl-no-stdinc">,
   HelpText<"HLSL only. Disables all standard includes containing non-native compiler types and functions.">;
 def dxc_Fo : DXCJoinedOrSeparate<"Fo">,
   HelpText<"Output object file">;
+def dxc_Fre : DXCJoinedOrSeparate<"Fre">,
+              HelpText<"Set output file name for reflection files">;
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inbelic wrote:

nit:
```suggestion
  HelpText<"Set output file name for reflection files">;
```

https://github.com/llvm/llvm-project/pull/181258