Add aarch64 support

[maisatanel]

Fedora CoreOS provides aarch64 architecture compatibility, so Ucore can too.

[bsherman]

Looking for testing volunteers as well as those who would want to help setup the build for this.

Team uBlue is gaining some access to an aarch64 builder environment, so this could start to move forward.

[scottames]

I'm all-in with my workstation machines on ublue, just getting started with ucore. Count me in to at least help test this!

[endocrimes]

I have an ampere box I would like to use with uCore, so I'm happy to take a look at this.

@bsherman Do we have an aarch64 builder already? (If not I can start playing with this downstream and upstream stuff when we do)

[bsherman]

I have an ampere box I would like to use with uCore, so I'm happy to take a look at this.

@endocrimes Welcome and thanks for jumping in!

My understanding is we have a current blocker for aarch64, because the upstream container-native ostree images are not being properly built.

https://quay.io/repository/fedora/fedora-coreos?tab=tags shows that 4 different architectures are being built, but in fact, only amd64 binaries exist, despite the tagging.

I say this is my understanding, because, while I'm confident this is the case for the desktop images hosted there, I haven't verified this for fedora-coreos images.

@bsherman Do we have an aarch64 builder already? (If not I can start playing with this downstream and upstream stuff when we do)

I thought we had access to aarch64 builders (can you confirm @castrojo) but even if we don't yet, any progress made would be helpful. I will also point you to the Discord thread where some discussion has occurred.

[bsherman]

Noting here that @EyeCantCU confirmed for us that the quay.io fedora-coreos images should be good for aarch64 testing.