Add ENV variables for disabling colour stacktrace printing

[nickrobinson251]

Alternative option for closing #40228 (alternative to #40230)

Essentially I'd like to avoid the new light_black colour stacktrace printing which I find I can't really read, without having the run with julia --color=no

Couple comments on the approach:

• how many env variables might we end up needing here?
  • i've gone for two: 1 for the color printing of modules + 1 for the color printing of the location. Seems the simplest way to split up the options and close Improve visibilty of line location in stacktrace e.g. Ability to override/disable muted colour in stacktraces  #40228 ...I'd also be happy to remove the one for disabling module color, since that's not (yet) been requested.
  • (but we could have e.g. three: 1 for modules + 1 for the arguments + 1 for the location).
• should these be binary true/false or allow custom colours?
  • i've gone for binary true/false. Again, seems simplest. Also matches the existing JULIA_STACKTRACE_* variables.
    • by default (true) you get the color printing that Base sets
    • by setting false you can disable the color printing, recovering something very similar to the printing for Julia v1.0 - v1.5,
  • If we wanted to allow specifying colours we'd have to figure out how, and i don't have a use-case for that, and it seems more like the role of an external package anyway.

If this kind of solution seems acceptable, then i'd appreciate advice on what exactly should be included (i.e. places where the colour should be disabled by this flag), as i think the printing can be fairly complex (it's easy to miss a place).

Example

Default

With ENV["JULIA_STACKTRACE_COLOR_LINES"] = false

With ENV["JULIA_STACKTRACE_COLOR_MODULES"] = false too

[nickrobinson251]

Bump :)

Is anyone able to provide feedback on this?

Thanks