Adapt to latests Graal/Truffle version, moving from Arguments object to plain Object[] for method invocations

- receiver is treated as normal argument, no special handling anymore
  -> receiver is argument[0]
- don't need SelfArgumentReadNode anymore
- dispatch nodes do not need virtual frames anymore
- caller frame is not kept track of anymore, very much like in RTruffleSOM as well
- removed invokeRoot, now the conversion to SAbstractObject is done explicitly by caller

Signed-off-by: Stefan Marr <git@stefan-marr.de>