Add Support for `Async` openai instrumentation

[alizenhom]

Description

• Add wrapper around AsyncCompletions.create to instrument async openai functions
• Adjust StreamWrapper to include __anext__, __aiter__ & __aenter__

Type of change

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

How Has This Been Tested?

• [x] tox -e py312-test-instrumentation-openai-v2-0
• [x] tox -e py312-test-instrumentation-openai-v2-1

Does This PR Require a Core Repo Change?

• [x] No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• [x] Followed the style guidelines of this project
• [x] Changelogs have been updated
• [x] Unit tests have been added
• [ ] Documentation has been updated

[gyliu513]

/lgtm