This is required for more hermetic evals.
A simple thing to try is, before this change, replace `default.nix` with
`throw "No thanks..."`. It would throw. It was also possible to observe
`local.nix` was being included by the warnings.
Wioth this change, `release.nix` does not include `local.nix` through
`default.nix`.
I think this was the last piece of Mobile NixOS that actually relied on
`default.nix` being a thing. We have finally completely inverted the
control, where `default.nix` uses the helpers, rather than the helpers
evaluating a specialized `default.nix`.
From now on, it should be entirely safe to experiment with
`default.nix`. We should be able to **fail noisily** when a user builds
the default empty configuration!
This includes the whole `tested` job (a simple no-op for hydra), but
adds additional things we want to track success for.
`tested` is for the basic minimum we want to succeed.
`testedPlus` adds more exotic, and less well-tested platforms.
It's being replaced by the generic uefi-x86_64 device.
Basically, replace the QEMU-specific system type by the totally standard
UEFI system type. This way we're dogfooding it way better!
As thus rootfs is universal, building it will allow end-users to
directly be able to run a somewhat usable system on their devices, even
if they are unable to bootstrap themselves one.
Furthermore, this ensures that the requirements are built and do
continue building on aarch64-linux.
