[clang] [clang-tools-extra] Remove `StringLiteral` in favor of `StringRef` (PR #122366)

[Nikita Popov via cfe-commits]

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@@ -57,7 +57,7 @@ class DeclarationFragments {
     Keyword,
     Attribute,
     NumberLiteral,
-    StringLiteral,
+    StringRef,
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nikic wrote:

Generally a lot of clang changes are wrong. There's a StringLiteral AST node, without relation to StringRef...

https://github.com/llvm/llvm-project/pull/122366