Allow Multiple Configuration Files

As someone who just migrated from the old caps2esc aur package it was a little confusing that I had to configure the caps2esc job myself given I had installed interception-caps2esc. We could do something similar to other programs such as NetworkManager and fontconfig where we have /etc/interception/interception.yaml as well as /etc/interception/conf.d/ for external configurations to be installed. This would also give users the option to split large configurations for convenience.