Make all written text built-in styles so that their styles can be customized

[kodie]

This makes it to where all text (for example help and prompts) can have their styles customized just as easy as it is to define a new custom style:

\Ahc\Cli\Output\Color::style('error', ['fg' => Ahc\Cli\Output\Color::BLUE]);
\Ahc\Cli\Output\Color::style('choice', ['fg' => Ahc\Cli\Output\Color::GREEN]);

Fixes #114

[dimtrovich]

well done @kodie . I've been meaning to look into this subject for a while now. I like this implementation. Nice work, thanks.