Shutdown SDK providers on process exit

[anuraaga]

Is your feature request related to a problem? Please describe.

Currently spans are not flushed on process exit, especially notable when instrumenting a CLI type of command rather than server. I could confirm adding a time.Sleep at the end fixes it, as well as getting the provider to shut it down manually

func main() {
	ctx := context.Background()

	tp := otel.GetTracerProvider()
	if sdktp, ok := tp.(*trace.TracerProvider); ok {
		defer sdktp.Shutdown(ctx)
	}

	...

Describe the solution you'd like

For application to be instrumented automatically to shutdown on exit - this behavior matches javaagent.

Describe alternatives you've considered

No response

Additional context

No response

[123liuziming]

I' will fix that, thanks for your feedback