feature: add multi-modal support for bedrock converse

[yarikama]

Description

Added multimodal support for the BedrockConverse integration, enabling image processing capabilities for models through Amazon Bedrock. This feature allows users to send both text and images to the model and receive text responses that reference or describe the provided images.

Key enhancements:

• Implemented image handling for BedrockConverse in accordance with AWS Bedrock API specifications
• Enabled streaming capabilities for multimodal content
• Created comprehensive integration test suite covering all supported use cases

New Package?

Did I fill in the tool.llamahub section in the pyproject.toml and provide a detailed README.md for my new integration or package?

• Yes
• No (Updating existing package)

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes
• No

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• I added new unit tests to cover this change
• I believe this change is already covered by existing unit tests

Added extensive integration tests including:

• test_bedrock_converse_integration_chat_multimodal: Tests synchronous multimodal chat
• test_bedrock_converse_integration_achat_multimodal: Tests asynchronous multimodal chat
• test_bedrock_converse_integration_stream_chat_multimodal: Tests streaming multimodal chat
• test_bedrock_converse_integration_astream_chat_multimodal: Tests asynchronous streaming multimodal chat

All tests verify proper handling of both text and image inputs, and validate appropriate responses.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added Google Colab support for the newly added notebooks
• My changes generate no new warnings
  
• I have added tests that prove my feature works
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods

[logan-markewich]

🔥

[logan-markewich]

LGTM! Thanks!