systemd auto install

**Basic info**
Game: LinuxGSM general
Distro: Systemd supported distros

**Is your feature request related to a problem? Please describe.**
Systemd is the standard way of managing services and starting on boot. However, it is not "simple" to use for a standard admin. It would be a good idea for convenience for the LinuxGSM script to install systemd script specific to itself and be able to also remove the systemd script as well.

**Describe the solution you'd like**
Automated installation of systemd using a new LinuxGSM command

**Describe alternatives you've considered**
The admin manually adding the script