[llvm] Add the 'initialized' attribute langref and support (PR #84803)

[Jan Voung via llvm-commits]

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@@ -186,6 +193,9 @@ class Attribute {
   /// Return true if the attribute is a type attribute.
   bool isTypeAttribute() const;
 
+  /// Return true if the attribute is a const range list attribute.
+  bool isConstRangeListAttribute() const;
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jvoung wrote:

nit: wonder if should s/Const/Constant/ to be consistent with isConstantRangeAttribute, etc.

https://github.com/llvm/llvm-project/pull/84803