[Enhancement] Add an option to specify multiple platforms

[zoof]

Unless I am mistaken, there is no way to specify multiple platforms. The problem with allowing just a single platform is that in trying to mirror conda-forge for a particular platform/python version, noarch packages are not included, even when include_depends: True is specified. Allowing the inclusion of the noarch platform would fix this problem.

Alternatively, specifying a platform (linux-64, win-64, etc.) could default to also downloading any noarch dependencies when include_depends: True is invoked.