Feature request: colorized output

This is a feature I started working on long ago for Hanami: https://github.com/hanami/hanami/pull/906

There could be two parts to this:
- Colorizing the output of `dry-cli`, like each command's `help` and the list of subcommands
- Adding something like `say` that users of the library can use to print in color (instead of using `print`).

e.g.
```ruby
say "create", color: :red
```

This should probably be like `print` rather than `puts` (no trailing newline), since people should be able to print in several colors on one line.

The concrete use-case for this could be like hanami/hanami#906, being able to colorize the output of file generation for Hanami.

Is this something we'd be interested in adding to `dry-cli`? Any thoughts on the API?