Opportunistic optimizations in translating lambdas

Some lambdas can be entirely represented by method handles, such as :

  (args...) -> staticMethod(args)
  (first, rest...) -> first.instanceMethod(args)
  t -> t.a
  (t, v) -> { t.a = v; }
  () -> ClassName.staticField;

Rather than desugaring the lambda body to a method, and putting a method reference to that in the constant pool, we can just compute the appropriate method handle that is equivalent to the lambda body instead, and put that in the static bootstrap argument list.