[Renderer] Move MM Hash parsing into Renderer

[DarkLight1337]

Purpose

Follow-up to #34560

• Normalize MultiModalUUIDDict -> MultiModalUUIDItems in Renderer instead of MM processor.
• Remove tokenization_kwargs from MM hash calculation as the MM data isn't affected by that.
• Update MultiModalProcessor.apply argument list to put UUIDs before miscellaneous kwargs.
• Clean up MM data parsing. Replace _is_empty check with modality selection in get_dummy_mm_inputs.

Test Plan

Test Result

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
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[gemini-code-assist]

Code Review

This pull request refactors the parsing of MultiModalUUIDDict to MultiModalUUIDItems from the multimodal processor to the renderer, which is a good architectural improvement. The changes are propagated through many files, and the refactoring itself seems solid. However, I've identified a critical issue where tokenization_kwargs are no longer included in the multimodal cache hash computation. This could lead to cache corruption and incorrect model outputs. I've provided a detailed comment and a suggested fix for this issue.

[mergify]

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