Add Credo support

[maxencetholomier]

I've searched open issues for similar requests

• [x] Yes

Is your feature request related to a problem? Please describe.

First I want to thank you for your project, it really help me getting started on Neovim (coming from vim and CoC).

Would it be possible to integrate credo to the list of linters ?

This is the default linter for the elixir community :)

Thank you in advance

Describe the solution you'd like

It would be nice to download this as every other linter on Mason.

Describe potential alternatives you've considered

No response

Additional context

No response

[Conarius]

This one would require to first support the hex package manager in order to install it. When it used .local a lot it won't be supported likely. After that Credo can be added to the mason-registry. As of now, the easiest way is through mix project dependencies.