New Feature: ketos-train command

This merge request introduces a new command, ketos-train, to the Ketos commands suite. The ketos-train module simplifies the process of training a neural network model with the specified parameters and data, allowing integration of user-defined custom transformations, audio representations, and neural networks.

Key Features

• Training Neural Network Models: Provides functionality to train neural network models using user-defined configurations, including model recipes, HDF5 databases, and audio representation files.
• Custom Modules Support: Allows users to integrate custom neural network architectures, input transformation functions, and output transformation functions through a custom module directory.
• Batch Generation: Supports creating batch generators for training and validation data, handling multiple tables and custom batch sizes.