Refactored FCS-MPC implementation to align with environment-provided utilities and improve prediction logic

- Replaced manual abc → αβ → dq voltage transformations with environment's native method:
- Updated voltage vector table to use finite set directly from the environment via:

- Now storing and returning subaction **indices** instead of full abc voltage vectors for better integration and comparison
- Updated epsilon handling in prediction loop:
  - Epsilon is now incremented as
  - dq-transformation uses averaged value:
- Replaced hardcoded max_depth with  (renamed from  for clarity)

Previously, I was doing manual calculations: converting abc voltages to αβ and then dq using custom logic.
Now all transformations use the environment's own coordinate conversion function and finite action space, making the controller more accurate and modular.

Thanks again for the helpful feedback!

Author: manjeetjha070