Go binding: Start implementation of the Dict module

[michelchan]

Go binding: Finish implementation of the Dict module

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

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

The implementation should include all the functionality for Dict 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/