[Emmet] Completions appear inside open tag

[abitwhy]

The causes are probably not:

• Emmet self
  They have already solved it. And Vetur works properly.
• tsconfig.json
  As you see, it's a new volar-starter project.

[johnsoncodehk]

Reference code: https://github.com/microsoft/vscode/blob/c0769274fa136b45799edeccc0d0a2f645b75caf/extensions/emmet/src/defaultCompletionProvider.ts#L160-L218

[johnsoncodehk]

If someone wants to help in this, it should implement to https://github.com/volarjs/plugins/blob/master/packages/emmet/src/index.ts