Add compiler option -Qsource_in_debug_module for embedding source in debug builds to documented help text (#6597)

This commit adds the compiler option (-Qsource_in_debug_module) to the
help text.

New help text output below:

```
Utility Options:
  -dumpbin              Load a binary file rather than compiling
  -extractrootsignature Extract root signature from shader bytecode (must be used with /Fo <file>)
  -getprivate <file>    Save private data from shader blob
  -link                 Link list of libraries provided in <inputs> argument separated by ';'
  -P                    Preprocess to file
  -Qembed_debug         Embed PDB in shader container (must be used with /Zi)
  -Qsource_in_debug_module
                        Embed source info in PDB
  -Qstrip_debug         Strip debug information from 4_0+ shader bytecode  (must be used with /Fo <file>)
  -Qstrip_priv          Strip private data from shader bytecode  (must be used with /Fo <file>)
  -Qstrip_reflect       Strip reflection data from shader bytecode  (must be used with /Fo <file>)
  -Qstrip_rootsignature Strip root signature data from shader bytecode  (must be used with /Fo <file>)
  -setprivate <file>    Private data to add to compiled shader blob
  -setrootsignature <file>
                        Attach root signature to shader bytecode
  -verifyrootsignature <file>
                        Verify shader bytecode with root signature
```

fixes #6028

---------

Co-authored-by: Cooper Partin <[email protected]>

Author: coopp

include/dxc/Support/HLSLOptions.td

@@ -498,8 +498,8 @@ def Qembed_debug : Flag<["-", "/"], "Qembed_debug">, Flags<[CoreOption]>, Group<
   HelpText<"Embed PDB in shader container (must be used with /Zi)">;
 def Qstrip_priv : Flag<["-", "/"], "Qstrip_priv">, Flags<[CoreOption, DriverOption]>, Group<hlslutil_Group>,
   HelpText<"Strip private data from shader bytecode  (must be used with /Fo <file>)">;
-def Qsource_in_debug_module : Flag<["-", "/"], "Qsource_in_debug_module">, Flags<[CoreOption, HelpHidden]>, Group<hlslutil_Group>,
-  HelpText<"Generate old PDB format.">;
+def Qsource_in_debug_module : Flag<["-", "/"], "Qsource_in_debug_module">, Flags<[CoreOption]>, Group<hlslutil_Group>,
+  HelpText<"Embed source code in PDB">;
 def Qpdb_in_private : Flag<["-", "/"], "Qpdb_in_private">, Flags<[CoreOption, HelpHidden]>, Group<hlslutil_Group>,
   HelpText<"Store PDB in private user data.">;