allow color config for --list

[zachvalenta]

why

Too dark output from just -l was a blocker to me adopting just, saw that it was covered by #1294 and figured I'd have a go.

before

after

how to

Can config via:

• env var

JUST_LIST_RECIPE_COLOR='#a6e3a1'
JUST_LIST_DOC_COLOR='#f9e2af'
JUST_LIST_ALIAS_COLOR='#cba6f7'
JUST_LIST_GROUP_COLOR='#f38ba8'

• flags

just 
    --list-recipe-color '#a6e3a1' \
    --list-doc-color '#f9e2af' \
    --list-alias-color '#cba6f7' \
    --list-group-color '#f38ba8' \
    --list

[casey]

Thanks for the PR!

See my comment here I think this is really an issue with the terminal, and since terminal colors already have a mechanism to configure them, it's not clear that we should add that functionality to Just.