This reboots the system instead of starting a shell on boot problems.
Because the slot will only be marked as sucessfully booted as the last
step in a normal boot, repeated emergency boots will cause a fallback at
the boot chooser level to the other slot.
Testing this is possible by passing 'emergency' via the kernel command
line.
Move the default file list to a separate file in /etc/sysmocom/backup.d,
which is itself included in the backup. Also create a symlink to the
most recent backup.
We have some images that need the real wget for upgrades, the SSL
root certificate of CA-Cert but that doesn't use task-sysmocom to
build the image. Move these utilities into the tools task.