Process to update nightly from Foreman 2.6 to Foreman 3.0

Attempting to capture everything we need to update to change the nightly version from 2.6 to 3.0. This was mostly derived from the branching procedure.


Turned out this requires also bumps to hammer plugins, as they pin hammer_cli_foreman to < 3…

All of these now have been merged and released and packaged.

Thanks everyone involved!