[Bugfix] Do not crash V0 engine on input errors

[joerunde]

This PR adds exception handling to the V0 engine that catches errors processing the input for a sequence group, and removes that sequence group from the current batch instead of crashing the entire engine. We see this a lot when processing invalid image data for multimodal models, the mllama models are particularly bad offenders.

With this change, users will receive a 400 instead of a 500 when their request fails input processing in the engine, and other running requests will continue to process instead of also receiving 500s.

[github-actions]

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