feat: implement the ruby module

[AZanellato]

Description

Motivation and Context

There isn't a ruby prompt, which is one more language for the prompt.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Screenshots (if appropriate):

How Has This Been Tested?

• I have tested using MacOS
• I have tested using Linux
• I have tested using Windows

Checklist:

• I have updated the documentation accordingly.
• I have updated the tests accordingly.

[matchai]

Thank you for taking the time to add a Ruby module! 😄
Your PR looks great. Before we merge it in, can we add a Ruby heading to the config docs? The only configuration that should be present is the disabled option. https://github.com/starship/starship/tree/master/docs/config

Also, it would be great if we could add "Ruby" to the features list on README.md! 💎

[matchai]

Thank you for your contribution!
The PR looks good to me. 😄

[matchai]

@all-contributors please add @AZanellato for code, docs and tests.

[allcontributors]

@matchai

I've put up a pull request to add @AZanellato! 🎉