Add trivial r10k integration point.

[jcpunk]

Installation and configuration of r10k is out of scope. This merely provides a simple way to use it with the git repo workflow.

In my experience r10k also tends to use the isolated environment types from https://www.puppet.com/docs/puppet/7/environment_isolation.html

[ekohl]

FYI: I first want to get #841 merged to get CI green again and then I'll ask you to rebase this and your other PRs.

[jcpunk]

Sounds good, I'll try to keep an eye out, but if I miss it let me know and I'll get rebasing :)

[ekohl]

In case you missed it, it was merged.

[jcpunk]

:) Rebased my various PRs

[ekohl]

Something I've been thinking about: r10k (and g10k for that matter) can both update environments based on a git repo. Instead of running r10k for every environment that was updated, would it make sense to instead look at an entirely different hook script that just runs r10k as post-receive?

The one consideration may be that r10k may not be able to do git submodules, though that may be acceptable for many users.

[jcpunk]

My understanding is the r10k native git integration requires a bunch more config stuff. That could be an interesting point of integration, but is probably a bit of work...

The branch mapping feature is also something handy I'm not sure is in r10k directly.