feat(bedrock): allow text and content in Bedrock document sources

[Ratish1]

Description

This PR resolves an issue where providing a document source as text to the BedrockModel would cause an error because bedrock updated their DocumentSource definition https://docs.aws.amazon.com/bedrock/latest/APIReference/API_runtime_DocumentSource.html .This PR updates the DocumentSource type and modifies the request formatting to correctly pass through any valid source type (bytes, text, content). Unit tests were added to verify the format request with bytes, text and content,

Related Issues

Closes #1066

Documentation PR

N/A

Type of Change

New feature

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

• I ran hatch run prepare
• I ran formatters, linters and unit tests

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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