Consider use of Java 8 `LambdaMetafactory` for Afterburner getter/setter access

As per:

https://www.optaplanner.org/blog/2018/01/09/JavaReflectionButMuchFaster.html

it seems like there is a way to actually get near-static access for getters, without (explicit) code generation, using Java 8 added class `LambdaMetafactory`. Whether it will actually work out or not remains to be seen -- and, if it does, could it actually be added in `jackson-databind`? -- but seems like a promising lead. While mechanism is probably not enough to cover all code generation needs (field access, constructor calls), getter/setter access is significant on its own.