Create golang contrib "monorepo".

[toddbaert]

This need not actually be a "monorepo", but we might want to create a single repo that holds a collection of go projects.

Definition of done:

• project created
• readme explaining what it is, how it's structured
• basic CI (not formal releases)

Might want to be done in conjunction with: https://github.com/open-feature/golang-sdk-contrib/issues/2

[james-milligan]

https://github.com/open-feature/golang-sdk-contrib