`vp migrate` handles migration from `.nvmrc`

[TheAlexLichter]

Description

As a dev using Vite+, I want my old nvm files being migrated over to the Vite+ way.

Suggested solution

Ask them if they want to migrate them over when being used.

Alternative

Also adhere to .nvmrc (meh)

Additional context

Same for other node version managers!

Validations

• Read the Contributing Guidelines.
• Confirm this request is for Vite+ itself and not for Vite, Vitest, tsdown, Rolldown, or Oxc.
• Check that there isn't already an issue requesting the same feature.