feat(ls): provide OpenAPI 3.1.0 completion rules for XML object (#2171)

Author: tim-lai

packages/apidom-ls/src/config/openapi/xml/completion.ts

@@ -49,6 +49,20 @@ const completion: ApidomCompletionItem[] = [
       { namespace: 'openapi', version: '3.0.3' },
     ],
   },
+  {
+    label: 'prefix',
+    insertText: 'prefix ',
+    kind: 14,
+    format: CompletionFormat.QUOTED,
+    type: CompletionType.PROPERTY,
+    insertTextFormat: 2,
+    documentation: {
+      kind: 'markdown',
+      value:
+        'The prefix to be used for the [name](https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md#xmlName).',
+    },
+    targetSpecs: [{ namespace: 'openapi', version: '3.1.0' }],
+  },
   {
     label: 'attribute',
     insertText: 'attribute ',