Added support for Bedrock Titan Embeddings v2

[brycecf]

Description

• Added support for Bedrock Titan Embeddings v2. This version introduces new parameters to the request body, dimensions and normalize, so added new field, titan_body_kwargs, to support.
• Renamed model field to model_name to adhere to that used in parent class, BaseEmbedding. Bumped to 0.2.0 consequently.
• Fixed bugs with provider mappings.
• Improved unit test quality.

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?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [x] Added new unit/integration tests
• [x] I stared at the code and made sure it makes sense

Suggested Checklist:

• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] I ran make format; make lint to appease the lint gods