Before, including apt::unattended_upgrades on a host without
the unattended-upgrades package would fail on the first run,
because the module tries to install the package before apt is
finally configured.
This commit does:
- introduce the option $refresh_apt for apt::apt_conf
(Defaults to true). Can be used to not trigger Exec['refresh_apt']
- install the unattended-upgrades package after a final
Exec['refresh_apt']. To not run into a loop, it calls
Apt_conf['50unattended-upgrades'] with the option
refresh_apt => false, which is also not needed for the configuration
f16a0727dc