Update deployment to gpt-4o

[thivy]

This pull request includes significant updates to the migration documentation and infrastructure configuration to support the new GPT-4o model, which merges GPT-4 and GPT-4 Vision models. The most important changes include updating the migration guide, modifying infrastructure parameters, and removing configurations related to the GPT-4 Vision model.

Documentation Updates:

• docs/migration.md: Updated the migration guide to version 2.1, detailing the merge of GPT-4 and GPT-4 Vision models into the GPT-4o model.

Infrastructure Configuration Updates:

• infra/main.bicep: Updated parameters to support the new GPT-4o model and removed parameters related to the GPT-4 Vision model. [1] [2] [3]
• infra/main.json: Updated default values for parameters and removed configurations related to the GPT-4 Vision model. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]
• infra/resources.bicep: Removed parameters and resources related to the GPT-4 Vision model. [1] [2] [3] [4] [5]

[davidxw]

Reviewed and tested, some small fixes

[orngeatom]

quick question for you guys, if i do a pull and update necessary parameters would it remove any of the extensions/prompts/services added? I think not since they are stored in Cosmos. Trying to understand best way to merge this