Use bootc to add kargs

[castrojo]

This is how we're doing kargs:

bluefin/system_files/shared/usr/libexec/ublue-system-setup

Line 34 in 1cce6d9

KARGS=$(rpm-ostree kargs)

And here's how we're supposed to do it with bootc:

https://containers.github.io/bootc/building/kernel-arguments.html

[fiftydinar]

Note that users must explicitly use bootc update instead of rpm-ostree update to get kargs applied.

[p5]

Yeah, so I think this will have to go on the backlog for when bootc gains local layering support.

It'll break a few things if we do it too soon. And I don't think we should do it when we disable rpm-ostree local layering by default either, since people will want (or need) to overwrite it.

[castrojo]

What breaks specifically? I'm talking about in the container build steps not the runtime stuff (since rpm-ostree is still on the image). Will that break?

[tulilirockz]

@castrojo I believe we should test this on Achillobator. There we arent using rpm-ostree at all on deployed systems