Image support in `MetaLlamaChatGenerator`

[anakin87]

We want to make this component support multimodal user messages.

Relevant info: https://llama.developer.meta.com/docs/features/image-understanding

[anakin87]

I tested it with Llama-4-Scout-17B-16E-Instruct-FP8 and Llama-4-Maverick-17B-128E-Instruct-FP8
and already works properly!