better typings for useNuxtApp

[bendwarn]

Describe the feature

Now in VSCode with Volar const { doesNotExist } = useNuxtApp() will pass without error and recognize it as any. I know here needs to contain something from plugin or module, so wondering whether it is possible to improve?

Additional information

• [x] Would you be willing to help implement this feature?
• [ ] Could this feature be implemented as a module?

Final checks

• [X] Read the contribution guide.
• [X] Check existing discussions and issues.