Fixes support for cross region inference

[3coins]

Fixes #239

1. Fixes streaming for cross-region inference models ids.
2. Adds support for Cohere models in ChatBedrockConverse.
3. Also, adds standard integration tests for Cohere.

[3coins]

@efriis
Can you plz make sure CI account has access to the cohere.command-r-plus-v1:0 model.

[rsgrewal-aws]

@3coins why do we need the provider values and why do we need to parse the model id ? can we simply use the model id as is ?