Add a JVM -XX:+SharedArchiveFile=<file-path> diagnostic option to facilitate the writing of CDS tests.

Currently, the CDS shared archive path is hardwired to be <JVM_PATH>/classes.jsa. This makes it difficult to write tests for CDS because the tests will fail if the tester does not have write privileges to <JVM_PATH>. As a result, CDS is not tested as well as it could be.

To make it easier to write CDS tests, add a diagnostic option, called SharedArchiveFile. The SharedArchiveFile option would take a string specifying the path of the shared archive file. For example, this would specify that the shared archive file is /tmp/my_classes.jsa.

java -XX:+UnlockDiagnosticVMOptions -XX:SharedArchiveFile=/tmp/my_classes.jsa -Xshare:dump

The option would need to be specified when writing the archive (-Xshare:dump) and when reading it (-Xshare:<on|auto>). The default value would be <JVM_PATH>/classes.jsa.