Fix marker padding

[brendanzab]

I broke the padding in c1a382e due to my misunderstanding of what was going on. I've created a new Pad datatype to make it clearer.

Following rustc's lead I've also:

• made the secondary labels use a different styling to the primary labels,
• used blue coloring rather than cyan for the line numbers

[Marwes]

So the blue styling is actually rather dark which makes it hard to see on dark terminals (at least on mine) which is why I used cyan instead as that is what ripgrep uses. rustc does not use either of those colors though if we want to use that same as it.

[Marwes]

Seems like rustc special cases this to use cyan on windows https://github.com/rust-lang/rust/blob/c3fd5d0ddead5b14ce5321b06bc5bed60d0cdf2f/src/librustc_errors/emitter.rs#L1483-L1487

rust-lang/rust#36178

[brendanzab]

Ah, interesting! Are you on windows then?

[Marwes]

Yep, but using Git Bash which seems to still have the issue (but it might just be my colorscheme, need to double check that actually).