How to use GameCI's Unity Editor containers with a non-GitLab/GitHub Actions environment?

Hi there,

I have been keeping an eye on these docker containers of the Unity Editor for some time now and I like the concept - allows me to run builds of my game server projects on a build box rather than waiting for a compile to take 10 minutes on my workstation.

However, one of the biggest gripes I have with these is the lack of instructions for integrating these containers with a non-GitLab or non-GitHub CI flow like Jenkins. A very minor percent of the community would probably not use these automation workflows (myself included) and prefer to have in-house build boxes.

It would help to have documentation on how to, say, use the docker containers to generate a license request and activate it, so the containers can spit back a secret or license data. Then I would paste that data into Jenkins so it can pass it along to the container being spun up when compiling the Unity project.

### But wait, there's more.
Speaking of the generating license request, how is this done? Do I launch the `unity-hub` container with an argument saying that I want to generate a license for the build machine ID, then following the steps in the FAQ? Or do I use the `unity-editor` container?

In other words, how do I generate the license request via the command line, not inside a Github or GitLab CI action?

I think last time I tried, I was able to login to my personal Unity account but was unable to apply the licensing or something. Manually trying to fix it up eventually got it to a "Machine ID mismatch" error and then I just gave up.

Help would be appreciated. Thanks!