Add EventName to LogRecord

[DylanRussell]

The event.name attribute has been deprecated in favor of a top level EventName string field in the LogRecord.

See open-telemetry/opentelemetry-specification#4260 (comment)

It no longer makes sense to have an Event class at all now.. An event is just a LogRecord with the event name field set..

I think we should revisit events, and look at the approach that they took in go lang (open-telemetry/opentelemetry-go#6018), where the only change they made to support events was to add the EventName string field to the LogRecord.. In order to emit events, a user simply calls LoggerProvider.emit with a LogRecord that has the event name set.. That's it.

Wondering what others think of doing it that way. Given events are still in alpha, i don't think it's too late to make this change.

[aabmass]

It no longer makes sense to have an Event class at all now.. An event is just a LogRecord with the event name field set..

That's right, the Events API was deprecated and there is just Logs API now. This will be a bit disruptive to remove since some contrib instrumentations and users depend on the events API. A good first step is to mark the main events functions as deprecated (e.g. EventLoggerProvider, get_event_logger, ...)

[DylanRussell]

Sent out #4654 to mark events API/SDK as deprecated