Inject `PNPM_CONFIG_RUNTIME=false` when `vp env` is `managed`

[liangmiQwQ]

Description

pnpm itself has a runtime version management system, means the same Node.js version might be downloaded twice by both Vite+ and pnpm.

Suggested solution

When vp env is set to managed mode, we can inject PNPM_CONFIG_RUNTIME=false in the shell script.

Also, when users call vp env off / vp env on, Vite+ should also change the status of this env variable.

This can be also shown in vp env doctor (Suggested by @ TheAlexLichter)

Alternative

N / A

Additional context

Context: https://discord.com/channels/1475973262193459293/1479410337223802951/1538525485166760026

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.

[liangmiQwQ]

IMO, I support to do this change.

[fengmk2]

+1

[liangmiQwQ]

Inspired by @ BlankParticle, I thought of a possible issue

There are some users who use Bun / Deno as their runtime, and pnpm as a package manager, where pnpm also manages these runtimes.

If we do this change, it might influence these users, and then they have to use vp env off here.

[liangmiQwQ]

I think a good way to do that is to inject this variable in vp install, it needs to detect whether the project declare node as runtime. I will handle this after the PM refactor.