For Map iteration, this avoids creating intermediate Set and
Iterator objects, plus all the transient Map.Entry objects. For
List iteration, this eliminates the Iterator. Both cases may
require allocating the lambda object and introduce boot-time
overhead to instantiate the lambda class, but overall this patch
should reduce allocation along these paths.

This may not improve load times since we only do this once for
each bound class, rather than doing it for classes in that bound
class's hierarchy.

Note it's not really lazy yet because RubyToJavaInvoker calls
initialize immediately and most upstream logic eagerly prepares
the payload.

This commit also removes the intermedate installer for
constructors.

* Avoid repeated security exceptions by caching empty method lists
* Localize more method-gathering state and logic into
  MethodGatherer class
* Clean up some visibility and organization.