feat: add Vision Transformer (ViT) implementation for image classification

- Implement complete ViT architecture with patch embedding
- Add positional encoding with learnable CLS token
- Include scaled dot-product attention mechanism
- Implement transformer encoder blocks with layer normalization
- Add feed-forward network with GELU activation
- Include comprehensive docstrings and type hints
- Add doctests for all functions
- Provide example usage demonstrating the complete pipeline

Fixes #13326

Author: devvrat8848