Support for hits editing frontend

[Timtam]

Summary

We want to be able to edit your own hits in the frontend, allowing every instance to have their own set of hits, as well as making hit contributions easier.
This however is a huge undertaking, as it requires alot of useful, but time-consuming maintenance and rewriting steps.

Motivation

Currently, all hits are maintained inside an Excel sheet, which gets saved as CSV and can then be imported into the codebase. However, this Excel sheet only lives at @Timtam 's place and thus contributions are hard to maintain. Also editing inside the Excel sheet is annoying too as it doesn't really allow us to maintain hits included in multiple packs very well.