Add EEST Tasks to `new_fork.py`

We should add tasks required to create tests for a new fork:
- Add the new fork to [src/ethereum_spec_tests/ethereum_test_forks/forks/forks.py](https://github.com/ethereum/execution-specs/blob/forks/osaka/src/ethereum_spec_tests/ethereum_test_forks/forks/forks.py) and the new transition fork to [src/ethereum_spec_tests/ethereum_test_forks/forks/transition.py](https://github.com/ethereum/execution-specs/blob/forks/osaka/src/ethereum_spec_tests/ethereum_test_forks/forks/transition.py)
- Create the new fork folder in [tests/eest](https://github.com/ethereum/execution-specs/tree/forks/osaka/tests/eest)