Add option to install packages from npm

[Valentine-Mario]

This PR currently install packages but it's still rather slow.

Todo

• [ ] Add a bonnie.lock.toml file
• [ ] Cache downloads
• [ ] Write packages downloaded via cli arg to bonnie.toml file
• [ ] Increase performance
• [ ] Run post and pre install scripts

[arctic-hen7]

Okay! Sorry I couldn't get to this earlier, I've been really busy! I'm afraid as I mentioned in the issue relating to this, I'm not going to merge an entirely new implementation of a package manager. Bonnie is designed to be language-agnostic, it's not supposed to be tied to any one programming language.

What I would fully support is some kind of abstraction over the package managers of many languages, which allows us to depend on existing systems built for performance and the like. If you want to work on this (it's currently low priority for me personally), please open a new pull request. I don't mean to dismiss you, but I'm afraid I don't want to take this project in the direction of tying it to NodeJS by implementing a whole new package manager.