ChatAnthropicVertex: BlockType Image not supported

[qvalentin]

ChatAnthropicVertex does not support Images in the format that is documented in the the langchain docs: https://python.langchain.com/docs/how_to/multimodal_inputs/#images

In langchain-anthropic the image ContentBlocks are converted: https://github.com/langchain-ai/langchain/blob/6a5073b227feff67eae7ebf51cdc3bdc8d09c4b3/libs/partners/anthropic/langchain_anthropic/chat_models.py#L206

But this code is missing from _anthropic_utils of ChatAnthropicVertex https://github.com/langchain-ai/langchain-google/blob/main/libs/vertexai/langchain_google_vertexai/_anthropic_utils.py#L185