[clang-tools-extra] [clang-tidy] Preserve typedef comments in `modernize-use-using` (PR #180372)

[Baranov Victor via cfe-commits]

================
@@ -160,6 +160,86 @@ getTrailingCommentsInRange(CharSourceRange Range, const SourceManager &SM,
   return Comments;
 }
 
+std::string getSourceText(CharSourceRange Range, const SourceManager &SM,
----------------
vbvictor wrote:

I'd want to see optional<string> here.
It's not immediately clear that empty text is indication that something failed.
Impty text could mean no text at all.

https://github.com/llvm/llvm-project/pull/180372