Claude Messages API - Multimodal limit and documentation support

**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](https://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages.html#:~:text=You%20can%20include%20up%20to%2020%20images.%20Each%20image%27s%20size%2C%20height%2C%20and%20width%20must%20be%20no%20more%20than%203.75%20MB%2C%208%2C000%20px%2C%20and%208%2C000%20px%2C%20respectively.)

Start at the Bedrock invoke_model validation and compare its image and document handling with the linked Anthropic and Bedrock documentation. Done means the validation reflects the supported image limits and document content type behavior, with relevant validation coverage identified or updated if present.

Written by the indexing model from the issue text.