Claude Messages API - Multimodal limit and documentation support

[ekaya97]

Issue
The Anthropic Claude Messages API on Bedrock only allows for up to 20 images. However, Anthropic's own API allows up to 100 images if sized correctly.
Support for documents seems to have been removed. Content type document no longer works.

Impact
This limitation by Bedrock causes issues in document processing workflows. Documents with more than 20 pages cannot be proccessed without losing crucial context. Claude 3.7 is certainly able to process more than 20 pages.

Request
Update the Bedrock invoke_model validation to be aligned with Anthropic's API.

Supporting resources
https://docs.anthropic.com/en/docs/build-with-claude/vision#basics-and-limits
Bedrock Docs