[V1][VLM] Enable proper chunked prefill for multimodal models

[ywang96]

This PR will be merged after #9871 which supports chunked prefill of LMMs natively in V1.

The goals of this PR are:
- Refactor model interface to be compatible with both V0 and V1 engine implementation (calling encoder at model executable vs calling encoder at model runner)
- Add placeholder ranges to input processor of all LMMs so that placeholder locations can be precisely tracked for chunked prefill in V1 (and potentially prefix caching)

See comment

[github-actions]

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[ywang96]

The description has been updated to reflect the repurpose of this PR.

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @ywang96.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @ywang96.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[ywang96]

Closing as this PR is broken down into several small PRs

• [V1] Refactor model executable interface for all text-only language models #10374
• [V1] Refactor model executable interface for multimodal models #10570
• [V1] Initial support of multimodal models for V1 re-arch #10699