Refactorize embeddings

[Optimox]

Feature request

Creating an external module for embeddings generation would make code clearer.
Some improvement to skip this part if no embeddings are needed would also make the training faster (see #97 ).

What is the expected behavior?
Nothing would change, just code optimization

What is motivation or use case for adding/changing the behavior?
Code clearer and faster.

How should this be implemented in your opinion?

Are you willing to work on this yourself?
yes