Replace hardcoded ANSI colors with `printstyled`

[danielwe]

Hardcoded ANSI colors produce garbled output with IOContexts that don't support terminal colors. One example is Pluto; see the following screenshot:

This PR rewrites the affected @printf statements to use printstyled instead, which respects the attributes of the IOContext. With this change, the Pluto screenshot looks like this:

I made sure the step column still lines up:

For terminals that support it, colors and boldness are the same as before:

[rveltz]

cool! thank you