Warn on invalid cookie name

[benmccann]

Describe the problem

Latest version of cookie library accepts different cookie names. Need to tell anyone who is setting invalid name to stop so that we can upgrade cookie library in Kit 3.0

Describe the proposed solution

use regex from https://github.com/jshttp/cookie/pull/167/files

put it here: https://github.com/sveltejs/kit/blob/f3b638efbe092c55c709bddd513cf6ba46afc97d/packages/kit/src/runtime/server/cookie.js#L115

Alternatives considered

No response

Importance

nice to have

Additional Information

No response