Cleanup existing rubocop violations

[bastelfreak]

We currently have a bunch of rubocop violations listed in /~https://github.com/betadots/hdm/blob/main/.rubocop_todo.yml. This needs to be fixed or we need to disable cops we do not like.

[rwaffen]

see: /~https://github.com/betadots/hdm/pull/33/files

[tuxmea]

We are going to work on the single todos on a cop by cop or file by file basis.

[tuxmea]

This is permanent WIP. Closing this issue