Refactoring enemy generation module

[Tyago-Teoi]

This pr focuses on the enemy generation process, refactoring its code for better readability.
It also makes code changes to increase and facilitate its use in a wide scope of games.

The changes are summarized as:

• Refactoring of the script "EnemyGeneratorManager.cs" to handle only high level methods;
• Addition of classes to handle SearchSpace configuration in the Unity Inspector;
• Minor refactoring following Single Responsibility rules and class/variable name standards;
• Use of Strategy design pattern for the genetic algorithm's Fitness class, as each game can have its specific evaluation function for calculate its fitness.