Create nodecg-io CLI

[hlxid]

Description

As discussed on discord we want to have a nodecg-io cli that should do the following things:

• Install nodecg-io to an existing nodecg install. (still needs some polishing work)
  • Development installs which use the current master
  • Production installs which fetchs the packages as a tarball from npm and unpacks them
• Uninstall nodecg-io
• Generate new bundles that can use nodecg-io, including a selector which prompts the user which service he needs (Add bundle generation nodecg-io-cli#11).

This cli will get a new repository, which will propably be named codeoverflow-org/nodecg-io-cli, because the cli has no direct coupling on the core, services and other components so the repository should be separated too.

Random todo list:

• Setup CI
• Add unit tests
• Add option to dev install to also clone docs
• Error when using the cli with a old node version (<12)
• Setup semantic-release
• Implement update check and log if a new version has been release (similar to npm?)
• log error if a invalid command was passed (e.g. nodecg-io abc does not print a error currently)
• Update docs

[hlxid]

Current progress has been pushed to https://github.com/codeoverflow-org/nodecg-io-cli