now with crystal language support

[rrevi]

Description

Add a new prompt section (Tide Item) for the Crystal programming language (via a test exist check for a shard.yml file).

Motivation and Context

Motivation you ask, well Crystal is awesome and so is Tide, and as such, Tide should also support version prompts for Crystal projects.

Screenshots (if appropriate)

I would include screenshots, but am having trouble testing live on my Mac and my Fish shell (despite that make tests pass)

How Has This Been Tested

• [ ] I have tested using Linux.
• [x] I have tested using MacOS.

Checklist

• [ ] I have updated the documentation accordingly.
• [x] I have updated the tests accordingly.