Add hello-world example for cedar-go#267

Seth-jo wants to merge 5 commits intocedar-policy:release/4.10.xcedar-policy/cedar-examples:release/4.10.xfrom

Seth-jo:feature/cedar-go-hello-worldSeth-jo/cedar-examples-cedar-go-hello-world:feature/cedar-go-hello-worldCopy head branch name to clipboard