dear all,

i was writing the documentation of a guix.scm file, and i realized that there's an inconsistency among the three most used commands in this context:

so, there's:

- guix build --file

- guix package --file

and then there's:

- guix environment --load

- guix pack # has neither

i'd propose to change guix environment to also use --file, but maybe i'm overlooking something, so, please speak up if you think it's a bad idea!

i never used guix pack, but maybe that also deserves a --file argument?