AndHow.getGroupForProperty breaks security model by allowing GroupProxy access

[eeverman]

Describe the bug
AndHow is supposed to enforce the same scope model as Java: If code cannot 'see' the Property, it cannot access its value. The AndHow.getGroupForProperty method creates a backdoor by which application can see Properties that it wouldn't normally have access to and thus read the value of those properties. Here is an example:

public class MyClass {
  private StrProp MySecret....
  public StrProp PublicProp...
}
... somewhere else ...
{
  //This returns a list including MySecret, allowing access to its value
  AndHow. getGroupForProperty(PublicProp).getProperties();
}

There is no reason for this method on the AndHow class - Application code never needs to know which class contained a Property and it shouldn't care.

AndHow has this method because it implements the StaticPropertyConfiguration interface. There is an internal version of this interface, so this method was moved there (StaticPropertyConfigurationInternal).

[eeverman]

fixed by #623