[Model] Add multi-image input support for LLaVA-Next offline inference

[zifeitong]

@DarkLight1337 It's good to be reviewed now. I am following #7122 and not adding a new axis to input shape as outlined in #4194 (comment). Let me know what do you think.

• Guard models that don't support multi-image input ([VLM][Core] Support profiling with multiple multi-modal inputs per prompt #7126)
• Support images inputs of variable sizes in the same batch
  • Support images with different number of patches (e.g. {2×2,1×{2,3,4},{2,3,4}×1})
  • Support images with different number of features

Reference: #4194 (comment), #7122, #7392

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[DarkLight1337]

Quick heads-up that #7126 has been merged.

[DarkLight1337]

Some initial comments.

[DarkLight1337]

Thanks for adding this sanity check!

[DarkLight1337]

I am following #7122 and not adding a new axis to input shape as outlined in #4194 (comment). Let me know what do you think.

We can keep this for now since it's not breaking anything. A separate PR can be opened to address this if the need arises.

[DarkLight1337]

VLM tests are failing

[zifeitong]

VLM tests are failing

The issue is phi3v uses more than 1 placeholder stings (<image_1>, <image_2>, ...), and breaks the placeholder padding function. It should work after #7783 is merged.

[DarkLight1337]

Do you prefer to wait for #7783 or just copy the original CLIP padding code into phi3v?

[zifeitong]

Do you prefer to wait for #7783 or just copy the original CLIP padding code into phi3v?

It looks like #7783 will be merged soon. I'll rebase my PR once it's merged and rerun the tests.

[zifeitong]

/ready

[zifeitong]

@DarkLight1337 All tests passed. PTAL when you get a chance.

[DarkLight1337]

Thanks again for implementing this!