Fix Bedrock Converse streaming and token handling

[tzolov]

• Modify stream method to support recursive tool call handling
• Update token tracking and metadata merging for streamed responses
• Improve token usage calculation for tool use events
• Update test cases to handle new response processing

Resolves #1743

[ilayaperumalg]

Thanks for updating the tests! LGTM, merging.

[ilayaperumalg]

Rebased, squashed, fixed check style error and merged as 00ede3f5