[Clang][TableGen] Change ClangAttrEmitter to use const Record * (#110584)

This is a part of effort to have better const correctness in TableGen
backends:


https://discourse.llvm.org/t/psa-planned-changes-to-tablegen-getallderiveddefinitions-api-potential-downstream-breakages/81089

Author: jurahul

clang/utils/TableGen/ASTTableGen.h

@@ -319,8 +319,8 @@ class PropertyType : public WrappedRecord {
     return get()->getValueAsString(UnpackOptionalCodeFieldName);
   }
 
-  std::vector<llvm::Record*> getBufferElementTypes() const {
-    return get()->getValueAsListOfDefs(BufferElementTypesFieldName);
+  std::vector<const llvm::Record *> getBufferElementTypes() const {
+    return get()->getValueAsListOfConstDefs(BufferElementTypesFieldName);
   }
 
   static llvm::StringRef getTableGenNodeClassName() {