8169816: Move src.zip and jrt-fs.jar under the lib directory
Reviewed-by: alanb, erikj

8154403: JRT filesystem loaded by JDK8 with URLClassLoader is not closable since JDK-8147460
Reviewed-by: alanb

8141609: Need test for jrtfs that runs on JDK 8 to target a JDK 9 image
Reviewed-by: alanb, sundar
Contributed-by: felix.yang@oracle.com