Add chruby

[pusewicz]

Supersedes #92.

Being more explicit about the item (and the tools it is using) is better for the experience.

Users then can add whatever tool they use, such as rbenv or rvm as separate items.

[pusewicz]

Wiki documentation:

## chruby

| Variable        | Description                                | Type    |
| --------------- | -------------------------------------------| ------- |
| bg_color        | background color of chruby item            | color   |
| color           | color of chruby item                       | color   |
| icon            | icon to display next to the chruby version | string  |

[pusewicz]

I've rebased against main @IlanCosman.

[IlanCosman]

There are a few copy-paste errors, like deleting the tide_rust.* variables in the classic config. Also, you added in a tide_chruby_verbose_version that doesn't exist 😄

[IlanCosman]

Also, please add chruby to the tide_right_prompt_items list in each config, since it will now be automatically removed if type -q chruby fails.

[pusewicz]

@IlanCosman Done!

[IlanCosman]

@pusewicz Can I ask how you're using chruby through fish? I'd like to test it out in the wild.

[pusewicz]

Sure, I use it on macOS via Homebrew install of https://github.com/JeanMertz/chruby-fish.

Just follow the instructions.

Then install different ruby versions via https://github.com/sstephenson/ruby-build#readme.

[IlanCosman]

Bah I'm too lazy 😂 Do you know the difference between RUBY_AUTO_VERSION and RUBY_VERSION?

[IlanCosman]

Thanks for your contribution @pusewicz 😄

[IlanCosman]

Oh @pusewicz, can you add the chruby variable documentation to the wiki? Kind of annoying that it isn't better integrated.

[pusewicz]

@IlanCosman Done!