Include preprocessing from other repos

[Ludee]

Include code from:

• https://github.com/openego/data_processing
• https://github.com/open-fred/db

[Bachibouzouk]

@Ludee - do you want to move the preprocessing files from there to here and leave a note that they are here in the old repo? As this repo's name contains MaStR it might be a bit confusing that it is the place to go for openego and openfred as well.

[Ludee]

This issue is in the wrong repo. Move to dataprocessing

[Ludee]

Close since OEP upload is possible without scripts.