refactor: Added shared XML parser teardown helper (#1438)

## Summary

**What is the goal of this PR?**

Added `destroyXmlParser()` helper to replace the repeated 4-line parser
cleanup block (stop, clear callbacks, free, null) that was copyied
across 6 XML parser files.

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lib/XmlParserUtils/XmlParserUtils.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <expat.h>
+
+// Safely tear down an expat parser: stop processing, clear callbacks, free, and null the pointer.
+inline void destroyXmlParser(XML_Parser& parser) {
+  if (!parser) return;
+  XML_StopParser(parser, XML_FALSE);
+  XML_SetElementHandler(parser, nullptr, nullptr);
+  XML_SetCharacterDataHandler(parser, nullptr);
+  XML_ParserFree(parser);
+  parser = nullptr;
+}