Add new components for DiT model:

- Introduced `attention_wan.py` with implementations for WAN self and cross attention layers, including adaptive layer normalization.
- Added `time_pos_embeddings.py` for various temporal positional embedding strategies.
- Created `dit_data_process.py` for data handling in DiT model training, including batch processing and sequence length encoding.
- Implemented `dit_model_provider.py` for model configuration and instantiation of DiT models.
- Added utility functions in `edm_utils.py` for EDM sampling and scaling processes.

These additions enhance the DiT model's capabilities and streamline data processing and model configuration.

Author: sajadn