Remove setClusterContext

[mattwelke]

In https://github.com/ow-extended-runtimes/java-17/blob/main/src/main/java/com/owextendedruntimes/actiontest/Action.java, the method setClusterContext is problematic. It's weird that users would see that function because they shouldn't call it. It's only there so that the Proxy can inject the cluster context during setup for the action to reference during any invocation it wants to. Right now, the method is public because it exists in a different package from the Proxy class.

Solutions:

• Move into the same package as the Proxy class, so that the visibility can be changed to package-private. That way, users won't see it.
• Refactor the Action class and Proxy class. In the Action class, add a constructor that allows the context to be injected. In the Proxy class, use reflection to call the new constructor instead of calling the default constructor like right now.