OpenAI: implement streaming support

[kaylareopelle]

The OpenAI chat completions instrumentation should have support for streaming.

• Update the instrumentation to support streaming
• Implement the overall ai_monitoring.streaming.enabled config
• Update documentation to show Ruby supports streaming
• Verify support with the latest LLM agent spec

[workato-integration[bot]]

https://new-relic.atlassian.net/browse/NR-233292

[kford-newrelic]

Bumped. Will consider for a future quarter.