feat: add pkg import command

[aleclarson]

The pkg import command lets you incorporate an NPM package into your Radashi. You can re-export its functions, rename them, or exclude specific ones as needed.

The generated mod.ts module automatically includes any packages you've imported.

Motivation

This feature is designed to help you merge your favorite NPM utility packages with Radashi, your go-to utility library. It gives you more freedom to customize Radashi to fit your needs.

Why not just install the package directly?

Bringing trusted packages into one place has several benefits:

1. It simplifies dependency management.
2. It makes collaboration easier by establishing a clear set of recommended NPM packages for your team.
3. It allows you to use Radashi's tooling (CLI and VS Code extension) with these imported functions, which otherwise only works with native Radashi functions.