RFR 8216553: JrtFIleSystemProvider getPath(URI) omits /modules element from file path

[Sundararajan Athijegannathan]

Please review.

Bug: https://bugs.openjdk.java.net/browse/JDK-8216553
Webrev: https://cr.openjdk.java.net/~sundar/8216553/webrev.00/

Thanks,
-Sundar