Always dynamically allocate PropertyTable

- `Texture::~Texture` expects `props` to be dynamically allocated.

- `GetPropertyTable` returned a pointer to an existing `PropertyTable`
  but is expected to return a newly, dynamically allocated one.

- `PropertyTable::PropertyTable()` suggests that an empty `element`
  property is valid.

fix #46876
fix #45573

(cherry picked from commit 09bda3f140)

modules/fbx/fbx_parser/FBXDocumentUtil.cpp

@@ -160,7 +160,7 @@ const PropertyTable *GetPropertyTable(const Document &doc,
 			DOMWarning("property table (Properties70) not found", element);
 		}
 		if (templateProps) {
-			return templateProps;
+			return new const PropertyTable(templateProps);
 		} else {
 			return new const PropertyTable();
 		}