Quick fix to install regular .js npm packages

[DanielRosenwasser]

Let's say I start a new project. I start writing out an import for, say, express because I'm certain I'll be using that, but I haven't bothered to install it yet.

import express from "express";

Immediately, I might get an error like Cannot find module 'express'. because I didn't install the package before using it. This happens regardless of if I have noImplicitAny on. But this means I have to switch to a terminal and do an npm install.

We already give a quick fix to install missing @types packages, we should have a fix that

1. Gives the option of installing a missing package as a dependency or a dev dependency.
2. Also installs the types for that package if necessary in the same fashion.