refactor: rename CLI struct to ConsoleUI without changing behavior

[ptcodes]

Initially, I just wanted to address the following warning below by clippy and to change the CLI struct to Cli but we already had the Cli struct in cli.rs added by clap. That's pretty confusing.

I've renamed CLI to ConsoleUi and added a test. No changing behavior was introduced.

@vnepogodin please review.

error: name `CLI` contains a capitalized acronym
 --> src/cli.rs:6:12
  |
6 | pub struct CLI;
  |            ^^^ help: consider making the acronym lowercase, except the initial letter: `Cli`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#upper_case_acronyms
  = note: `-D clippy::upper-case-acronyms` implied by `-D warnings`
  = help: to override `-D warnings` add `#[allow(clippy::upper_case_acronyms)]`