Please review fix [2] for jpackage bug [1].Move `.jpackage.xml` file in `app` directory of app image and keep it in all OSX packages (dmg and pkg). Resotore copying of `libjli.dylib` into `$RUNTIME/Contents/MacOS` directory in MacAppImageBuilder.java.
Update jtreg test helpers accordingly.
- Alexey [1] https://bugs.openjdk.java.net/browse/JDK-8246792 [2] http://cr.openjdk.java.net/~asemenyuk/8246792/webrev.00
