Per MCO-476, we aren't guaranteed that this will happen, but as a "best effort" sort of thing we want to be ready in the event that the new ignition structures that support offline tang (for RFE-3271) are available, we can immediately consume them.

This will consist of:

• Rebase https://github.com/openshift/machine-config-operator/pull/2675 (the world kind of "moved around it" in some places)
• Decide whether to keep the "ignition applies kernel args" feature that's part of it (and seems to work)
• Add support for 3_4_experimental and test, so we can just swap in the real one when it's done?