Use anyhow for prettier errors on the console

[FichteFoll]

Since this application does not have a GUI at the moment but has a comparatively wide target audience, some clearer error message such as those provided by anyhow instead of the default output of panics on Result::unwrap (like in #33) might be helpful for users to figure out their issues more quickly (on their own).

Just an idea I'm putting up here.

Also, implementing proper bubbling of Errs until the main method will also be beneficial when a GUI is eventually added.

[IceDynamix]

related IceDynamix/reliquary#3

[FichteFoll]

Ah, I didn't even notice there was a separate library project. Indeed, reliquary should be using thiserror, whereas anyhow makes more sense for reliquary-archiver as the user-facing component.