feat: switch to akmods repo provided nvidia kmod

[bsherman]

This removes the akmod build process for nvidia drivers and the build of ublue-os-nvidia-addons from this repo, and instead installs said RPMs which are now built in the ublue-os/akmods repo.

Depends on ublue-os/akmods#53

[bsherman]

Leaving as a draft until akmods is built and this can test.

[bsherman]

Ok, at this point, I've tested this by building the silverblue-nvidia image locally, using the already published to ghcr akmods repo containing nvidia 535 kmod, and then pushing the image to a LAN local container registry and rebooting.

Seems to be working pretty well!

Note: we need to update the website repo docs to reflect these changes as the README contents for this repo have been migrated there.

[bsherman]

I'm not sure why the "Build akmods package" checks are expected, but they can be ignored. I'm hoping they clear after this is merged and a clean build occurs there.

[bsherman]

Marked as draft as @akdev1l and I are discussing some improvements to akmods which may be helpful before merging this.

[bsherman]

Updated: now depends on ublue-os/akmods#54

After the required akmods PR has been merged and built cleanly, this PR needs it's actions re-run to get a clean build.