[clang] [clang-format] Correctly annotate C# UTF 8 string literals (PR #211919)

[via cfe-commits]

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@@ -455,6 +457,28 @@ bool FormatTokenLexer::tryMergeCSharpStringLiteral() {
   return true;
 }
 
+bool FormatTokenLexer::tryMergeCSharpUtf8StringLiteral() {
+  if (Tokens.size() < 2)
+    return false;
+
+  auto Suffix = Tokens.back();
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owenca wrote:

```suggestion
  const auto *Suffix = Tokens.back();
```

https://github.com/llvm/llvm-project/pull/211919