[FEATURE] setup scripts

[SIMULATAN]

Is your feature request related to a problem? Please describe. As my used programs grow larger, I need to run plenty of setup scripts. These can be rather cumbersome. Another idea I had was to put some dotfiles that get updated way more regularly and thus would only clutter up your main dotfiles repo in another one. However, that requires additional effort.

Describe the solution you'd like A setup configuration option for every package that allows you to run scripts when deployed for ex. for the first time (saved to cache) This would also allow "script-only" packages that make it possible to configure things in a much more generic way (as in, you can not only symlink and copy whole files but also make scripts that configure applications via their CLI and such)

Describe alternatives you've considered Have pre and post deploy hooks with package granularity

If we can come up with a concept that we're happy with I'd be happy to try and implement this and make a PR. You did say that handling system packages is out of scope, but I think this feature would allow the creation of bridges between dotter and external programs that can handle that or something completely else.