Bedrock Cross-Region support

[csotomon]

Description

The latest versions of Claude and Llama models now support Cross-Region inferences, which require adding the region prefix to the model identifier. This fix enables the use of this feature by adapting our model handling to include the regional prefix.

Fixes # (issue) n/a

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
• [ x] No

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)

• [ x] Yes
• [ ] No

Type of Change

• [ x] New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Your pull-request will likely not be merged unless it is covered by some form of impactful unit testing.

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

Suggested Checklist:

• [x ] 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.
• [x ] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes
• [ ] I ran make format; make lint to appease the lint gods

[csotomon]

Should we also update bedrock converse?

I don't know what is bedrock converse, I checked the code in my project and now I can use the Claude 3.5 V2 without problem

[csotomon]

@logan-markewich can U approve this MR?

For next week I will make a code refactoring for simplify the library maintenance.