Implement events API

[lzchen]

https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/logs/event-api.md

[jeremydvoss]

Looking into this.

[riddlexu]

Hi, what's the current status of "events API" implementation in SDK? We want to use events API to handle the long running task. open-telemetry/opentelemetry-specification#3732
Thanks.

[lzchen]

@riddlexu

No implementation currently as of today.

[lzchen]

Closed by: #4054