feat(systemd/system): ignore disks if diskless

If the diskless parameter is sent in don't try looking for OEM or STATE
partitions.
feat(bin/ssh-keys-from-cmdline): initial commit

reads an ssh key from kernel commandline for PXE boot, etc
feat(systemd): add oneshot ssh-key-proc-cmdline

always attempt to add an ssh key given on the cmdline
Merge branch 'pxe-initial'