Refactor Order/Slot models

[KoalaSat]

What does this PR do?

Changes on this PR:

1. Clear differentiation between CurrentOrder (visited order on the order page) and ActiveOrder/LastOrder (orders associated to the slot)
2. Creation of the Order class. Any interaction with an order now happens through it.
3. Creation of the Robot class. Any interaction with a robot now happens through it.
4. Garage now is fully responsible of Orders and Robots.
5. Fixes the iterative code to check and notify about an active order
6. Federation and Garage Contexts now are fully decoupled and independent
7. Several bugs related to orders fixed. Probably some new introduced :)
8. A lot of simplification of code
9. Remove all different ...UpdatedAt variables and keep only slotUpdatedAt and federationUpdatedAt

Checklist before merging

• [x] Install pre-commit and initialize it: pip install pre-commit, then pre-commit install. Pre-commit installs git hooks that automatically check the codebase. If pre-commit fails when you commit your changes, please fix the problems it points out.