[Feature] Expose --color to as variable/function

[Maetveis]

It would be nice to allow recipes to query if just output is colored or not, recipes could use color whenever just output itself is colored.

Example (syntax for demonstration only):

color := if colored_output() == "true" {"always"} else {"never"}

compile:
   gcc --color="{{ color }}" foo.c

A justfile like this could be nice in CI to color subcommands (call via just --color=always), and still behave correctly when piped to a file.

As far as I see just can independently color its standard output and error streams, so it might make sense to provide queries for both.

[avi-cenna]

Is this related to #1186? The main issue for me right now is that when just echos the command that it's running, it prints it in white, and this gets lost amongst the other output. It is a small issue admittedly, but I feel like it would make the overall experience more pleasing.

[Maetveis]

Is this related to #1186? The main issue for me right now is that when just echos the command that it's running, it prints it in white, and this gets lost amongst the other output. It is a small issue admittedly, but I feel like it would make the overall experience more pleasing.

Perhaps slightly, the feature proposed here could be used to decide in a recipe whether to use the {{color}}/{{\color}} "tags" proposed in #1186, but implementation wise I'd think they are not related.