feat: improve distinction of flags and parameters

[mrdgo]

This PR does three things:

1. highlight = in --long-flag=value flags (orange in my case)
2. highlight flag identifiers as parameters (blue)
3. highlight string values as strings (green)

Before:

After:

Do we like these changes?

[fdncred]

I'm not a fan of everything being the same color. I kind of like the parameters being a different color from the commands. I do like the --time-style=long-iso color distinction. It's hard to tell on your theme, maybe your commands are yellow and the parameters are dark yellow?

[mrdgo]

The command is bold and green while strings are italic and green.

I would also be happy giving flag identifiers the type query:

These are not committed, yet!

[fdncred]

I like this most recent screenshot better. Lemme know when you're ready to land.

[mrdgo]

Last commit made exactly that happen :) From my side, this can be merged

[fdncred]

Thanks!