fix: color formatting detection on stdout

[blmaier]

Text printed to stdout by pixi has colors even when stdout is redirected to a pipe or file. For example:

$ pixi list | xxd -l 64
00000000: 1b5b 316d 5061 636b 6167 651b 5b30 6d20 .[1mPackage.[0m

It is a common feature for command-line tools to automatically detect if stdout is a pipe or file and disable colors. And in fact pixi uses the crate console for color formatting which has built-in support for detecting if stdout and stderr are terminals and automatically disabling color output, so this should work.

However pixi does its own color management which overrides how console manages color styling. Pixi checks if only stderr is a terminal, and based on that overrides console handling of stdout and stderr. Thus causing stdout to be color formatted when stdout is redirected to a file but stderr isn't.

Since console already has detection for both stdout and stderr, lets default to that. We only override console when pixi --color, PIXI_COLOR, or NO_COLOR are set.

As a bonus, this means pixi will now support the CLICOLOR spec that is implemented by console.

Fixes: #2536

[ruben-arts]

Thank you for this fix and simplification! I guess we were not properly aware of what console was already doing! Your change works for me!