Generate .pkg installers for Mac OS

[yuvipanda]

miniconda provides .pkg installers (https://docs.conda.io/en/latest/miniconda.html#macos-installers) that provide a more GUI method of installation. I think miniforge / mambaforge should generate these too! Would make for a better onboarding experience for some subset of users.

[yuvipanda]

conda constructor seems to support .pkg installations, so this is probably mostly fiddling with the build scripts?

[isuruf]

The hard part is signing those. Otherwise they come with big warnings about not being signed right?

[jakirkham]

Remember playing with this once, but seem to recall there will limitations about where the .pkg installers could install files. Is that still the case? Or am I misremembering?

[yuvipanda]

My hope is that given miniconda has them, miniforge / mambaforge could too!

I can see signing being the problem though.

[jaimergp]

I think we have all the elements to start prototyping a PKG installer with signing. I'll open a PR soon.

[psobolewskiPhD]

Gentle bump to this, as it would have some real value especially if they could be accessed from the lovely https://conda-forge.org page
Explaining the current install process is a bit tricky for people just getting their feet wet with command line, etc.

[jaimergp]

Feedback welcome in #434 :)