Support DiT Trainer

### Feature request

1. Refactor branch [dit](https://github.com/ByteDance-Seed/VeOmni/tree/dit) to use trainer. Training wan2.1 as example.
2. add vae & text encoder of wan2.1 and support wan2.1 inference.

### Motivation

Currently, training wan2.1 is not friendly in VeOmni.

### Your contribution

Support training and inference wan2.1. 