feat: Add support for command aliases

[Akmadan23]

I think it can be handy to have the ability to set custom command aliases (such as :q aliased to :quit), so I added a really simple implementation with a HashMap, which works fine for this task. For configuration I chose to put it in the main joshuto.toml because it's optional and if specified, the list isn't likely to be really long. Let me know if it's a welcome feature or if there's something you would do differently.

[kamiyaa]

Looks good, just minor styling. After its fixed I can merge it 👍

[Akmadan23]

I wasn't aware that cargo-fmt cares about imports order, from now on I'll always double check

[kamiyaa]

Thank you!