add modular blockset for wan 2.2 vace

[akshan-main]

What does this PR do?

Adds a modular blockset for Wan 2.2 VACE: Wan22VaceBlocks with a WanVaceEncoderStep for the VACE conditioning latents (control video, mask, reference images), a two-transformer Wan22VaceLoopDenoiser that forwards control_hidden_states as shared kwargs across the guider batches (same shape as the qwenimage controlnet denoise step), and a post-denoise reference-frame trim. Existing wan blocks are reused unchanged.

Outputs match WanVACEPipeline exactly with shared components and seed. One deliberate divergence: output_type="latent" returns the trimmed latents so they are directly decodable. Test components live in akshan-main/tiny-wan22-vace-modular-pipe.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline?
• Did you read our philosophy doc (important for complex PRs)?
• Was this discussed/approved via a GitHub issue or the forum? Discussed on Slack with @sayakpaul
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?

Who can review?

@yiyixuxu @sayakpaul

[github-actions]

Hi @akshan-main, thanks for the PR! It does not appear to link an issue it fixes. If this PR addresses an existing issue, please add a closing keyword (e.g. Fixes #1234) to the PR description so the issue is linked. See the contribution guide for more details. If this PR intentionally does not fix a tracked issue, a maintainer can add the no-issue-needed label to silence this reminder.