+proj #15180 adding akka-jmh, made ibench runnable from sbt

How to use:
```
project akka-jmh
;clean; compile; compile; run -i 1 -wi 1 -v extra -f 0
```

TODO:
* We must enable forked mode, currently not supported.
* We should not have to call compile twice - handle this automatically
* Make the -l option more user friendly - like testOnly