Deprecate the Kernel Extension

[tnek]

We're approaching 3 major versions since kexts have been deprecated. Deprecating the santa driver also cleans up all of the install scripts and makes maintaining/changing things in Common easier

[russellhancox]

I'd like for us to give time to users to provide feedback before we go ahead with this. While it's quite likely there are no remaining users of the kernel extension, not every organization upgrades macOS as promptly as {we do, they should} for various reasons.

We can post an announcement and RFC on the santa-dev group, a discussion on GitHub and possibly a notice to the MacAdmins slack #santa channel

[arubdesu]

I see the persuasive case being made there's process improvements that would come from being able to focus on the one officially supported low-level hook mechanism, since it currently isn't a choice Santa allows you to make on a recent OS. Is this just as simple as telling people on old OS versions to please continue using the releases prior to a specific tag? Munki has found that an easy-enough way to remove support for older OS versions without too much disruption that I can recall noticing.