Add APT config to base image

[schlusslicht]

This pull request introduces a minor alteration to the Dockerfile build stages: By creating an /etc/apt/apt.configuration file with appropriate values within the base build stage, all subsequent stages will inherit this configuration and no further arguments to individual invokations of apt-get have to be supplied.

The created /etc/apt/apt.configuration replaces the following arguments to apt-get globally:

apt-get -y --yes                   # APT::Get::Assume-Yes "true";
apt-get --no-install-recommends    # APT::Install-Recommends "0";
apt-get --no-install-suggests      # APT::Install-Suggests "0";
apt-get -o APT::Sandbox::User=root # APT::Sandbox::User "root";

[schlusslicht]

Please make sure all relevant build contexts support the heredoc notation!

[bkis]

The created /etc/apt/apt.configuration

❤️

[bkis]

Please make sure all relevant build contexts support the heredoc notation!

Yeah this feature seems old enough.