Timestamp properties in etw exporter

[treyhoffman84]

Is there plans to include timestamps in the etw exporter properties? I see timestamps in the metadata related to the span but not in the event properties.

[lalitb]

I think this was not added purposefully, as event-time can be obtained from the timestamp at the ETW layer, thus saving on network traffic. Feel free to add optional support (compile-time macro?) if you think it's required.