Automatically create macOS installer

[kenchan0130]

Motivation

Currently, we have to create the macOS installer with manual. However, this operation is slightly complicated.

We want to be able to update os with a very simple task.

Idea

Using Apple's sucatalog with script. And separate script from macOSUpgrade.sh.

Reference

https://github.com/munki/macadmin-scripts/blob/master/installinstallmacos.py can create sparseimage of macOS installer only.

[adammartin253]

I've been brainstorming ways to make this work as the task of caching a 6GB installer from your distribution points is tedious and it would make so much more sense to run a script within the script to pull down the installer from Apple's sucatalog. Happy to help with this @kenchan0130