Add minimum Node.js version warning to `sv`

[theetrain]

Describe the problem

I noticed someone running into cryptic errors when running npm create svelte@latest; it didn't recognize the await keyword due to Node.js 12 being used.

Describe the proposed solution

Have create-svelte check the installed Node.js version and fail on unsupported versions. Maybe this is as straightforward as adding an engines key to package.json.

Alternatives considered

No response

Importance

would make my life easier

Additional Information

No response