feat: generate a seed image
This exposes a `ssh-private-key` and `image` available under `@rules_labgrid//qemu/seed/image`. That can be used to set up a QEMU toolchain.
This exposes a `ssh-private-key` and `image` available under `@rules_labgrid//qemu/seed/image`. That can be used to set up a QEMU toolchain.