feat: add chatpgt-4o-latest model

[Digma]

Description

Add ability to use latest 4o model detailed here: https://platform.openai.com/docs/models/gpt-4o

The model brings performance improvements as shown in arena leaderboard that are important for experimenting with latest progress: https://lmarena.ai/

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)

• Yes
• No

Type of Change

Please delete options that are not relevant.

• 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 believe this change is already covered by existing unit tests

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes
• I ran make format; make lint to appease the lint gods