Go binding: Finish implementation of the Set module

[michelchan]

Go binding: Finish implementation of the Set module

Item	Detail
Binding	Go
Module	Morphir.SDK.Set
Relevant Morphir.IR.SDK module	Morphir.IR.SDK.Set
Relevant morphir-jvm code	morphir.sdk.Set
Relevant Elm Module	Set

Provide a Go lang implementation of the Morphir.SDK.Set module for Morphir.SDK.

The implementation should include all the functionality for Set as well as tests (we are willing to have this split across PRs).

Please place it here: https://github.com/finos/morphir/tree/features/polyglot-morphir/corelib/go/morphir/sdk/