Async activity Invocation Example in Go

[edmondop]

What was changed

This adds an example of a non-blocking invocation of two activities in Go, with a behavior coherent with the Java example here
https://github.com/edmondop/samples-java/blob/main/src/main/java/io/temporal/samples/hello/HelloAsync.java#L114

Why?

Checklist

1. Closes

2. How was this tested:

3. Any docs updates needed?

[cretz]

Add this example to the example list

[edmondop]

Fixed with a063d6c

[cretz]

If an err was reported by the first select, you have swallowed it

[edmondop]

Fixed with 7156e31

[mfateev]

We already have two samples that cover async activity execution:

https://github.com/temporalio/samples-go/tree/main/splitmerge-future
https://github.com/temporalio/samples-go/tree/main/splitmerge-selector

[mfateev]

This use case is already covered by existing samples:

https://github.com/temporalio/samples-go/tree/main/splitmerge-selector
https://github.com/temporalio/samples-go/tree/main/splitmerge-future

[edmondop]

This use case is already covered by existing samples:

https://github.com/temporalio/samples-go/tree/main/splitmerge-selector https://github.com/temporalio/samples-go/tree/main/splitmerge-future

Thanks! Didn't know those examples! If this pattern is what match more closely the Java async examples, maybe we can just update the README ?