Refactor all endpoints code

[acicovic]

Is your feature request related to a problem?

Our endpoints code is (maybe unnecessarily) scattered across files, has multiple levels of inheritance, and is generally complicated to follow/debug for contributors. As we keep adding more and more endpoints, this situation will only get amplified.

We need to refactor our endpoints to have code that is simpler and more maintainable in the long run.

Describe the solution you'd like

1. Plan
   • Look at the existing code. Brainstorm and take notes on how it could possibly be refactored/simplified.
   • Discuss the ideas and take any feedback into consideration.
   • If needed, before, during or after the discussions, work on some proof of concept code to help conclude the feasibility or to visualize how the end result could look like.
   • End-up with a final approach.
2. Implement