Add shims for Vue/Astro/Svelte files when migrating or creating #1278
Description
Describe the bug
When adding custom components, typescript is complaining (see #1007). Good DX would be asking the user if they want a default shim so TS is fine, until we have a way to type-check them with vp check.
Reproduction
Steps to reproduce
No response
System Info
-Used Package Manager
npm
Logs
Validations
- Read the Contributing Guidelines.
- Check that there isn't already an issue for the same bug.
- Confirm this is a Vite+ issue and not an upstream issue (Vite, Vitest, tsdown, Rolldown, or Oxc).
- The provided reproduction is a minimal reproducible example.