Use BaseExecutionEngine for Python and Numba engines

[datapythonista]

In #61032 we have created a new base class BaseExecutionEngine that engines can subclass to handle apply and map operations. The base class has been initially created to allow third-party engines to be passed to DataFrame.apply(..., engine=third_party_engine). But our core engines Python and Numba can also be implemented as instances of this base class. This will make the code cleaner, more maintainable, and it may allow to move the Numba engine outside of the pandas code base easily.

The whole migration to the new interface is quite a big change, so it's recommended to make the transition step by step, in small pull requests.