[VLM] Merged multi-modal processor and V1 support for Qwen-VL

[DarkLight1337]

(Not to be confused with Qwen2-VL (which is already supported) and Qwen2.5-VL (not supported yet))

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I have tested V1 locally and the model output is basically the same, but not entirely sure why an extra EOS token is being outputted.

V0 output:

# python examples/offline_inference/vision_language.py -m qwen_vl
The Tokyo Skytree tower is seen through cherry blossoms.
The Tokyo Skytree in the background with cherry blossoms in the foreground
The Tokyo Skytree is a must-see during cherry blossom season in Tokyo.
The Tokyo Skytree is seen through cherry blossoms in Tokyo, Japan.

V1 output (used TP=4 to avoid OOM locally):

# VLLM_USE_V1=1 python examples/offline_inference/vision_language.py -m qwen_vl
The Tokyo Skytree tower is seen through cherry blossoms.<|endoftext|>
The Tokyo Skytree is a must-see during cherry blossom season in Tokyo<|endoftext|>
The Tokyo Skytree is a must-see in Tokyo in spring<|endoftext|>
The Tokyo Skytree is seen through cherry blossoms in Tokyo, Japan.<|endoftext|>

I'll work on updating the model development guide with an example of custom HF processor in another PR.

[github-actions]

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