Actor method names need caps

**Describe the bug**
When using the `ImplActorClientStub` method, only functions that are public, ie. start with a capital letter in Go are recognized... however, I have an actor server written in Javascript that has method names starting with a lower case... how do I call them from a Go client?

Start by tracing the ImplActorClientStub method lookup and how it handles method names that begin with lowercase letters. Reproduce the call against a JavaScript actor with a lowercase method, then verify that a Go client can invoke it successfully without breaking existing public-method calls.

Written by the indexing model from the issue text.