Add optional color to error messages

[andychu]

Maybe the colors should be controlled by an option, like shopt -s color-errors

Not to go overboard, but we might want some notion of styles:

• single line -- IIRC may be required to make the errors coherent
  • e.g. if multiple processes in a pipeline fail (errexit), then we don't want the errors to interleave
• multiline (current style)
  • we should add recursive attribution information, like #346
• multiline and color
  • should the colors be customizable? how? most compilers probably don't let you customize them

[andychu]

I want to tackle this soon

[andychu]

copying comments:

I think color error messages like Clang/GCC can be more concise and readable, but there are some pitfalls:

https://lobste.rs/s/rcdj1z/hard_part_learning_language#c_e5y0gn

solution could be to respect

https://no-color.org/