Add preprocessing script and dataset inspection notebook for Omani TTS dataset

Refactor code structure for improved readability and maintainability

Add OmaniTTSDataset for annotated Omani corpus and fine-tuning notebook

Add WaveRNN dataset class and update hyperparameters for training

Refactor dataset path handling in hyperparams and model; update .gitignore to include environment files

Update dataset path in hyperparams and model; add training test script

Add support for Arabic characters in Tokenizer and update imports