Improvement: Make rules_python a dev dependency

### What

Right now rules_python is not a dev dependency because a target in the top level BUILD file requires it.
Bazel always evaluates top level targets and because of that our users will need rules_python.

### How

- Create a test to check that the module can be integrated
- Move the target depending on rules_python to a different location
- Make rules_python a dev dependency
- Make sure that the module is still integratable

### Estimates for realization

The highest risk is that we declare it as dev dependency when it is not. In that case the users would get a failure on integrating. This risk needs to be minimized by adding a test for it.
The test is what most probable will take most of the time to implement that. Moving the target should be trivial.

### Category

- [ ] Affects Detailed Design

### Requirements / Architecture

- [x] Requirements / Architecture are not affected by this change?