[Feature] Support VAE batch

[okotaku]

Motivation

VAEs have high memory requirements, especially when processing large batches of data. To reduce the memory usage, we can use a VAE batch forward technique.
Based on https://github.com/huggingface/diffusers/blob/v0.26.2/examples/research_projects/controlnet/train_controlnet_webdataset.py#L1306-L1309

Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

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📚 Documentation preview 📚: https://DiffEngine--132.org.readthedocs.build/en/132/