RFR(S): 8243947: [TESTBUG] hotspot/jtreg:hotspot_appcds_dynamic fails when the JDK doesn't have default CDS archive

[Calvin Cheung]

JBS: https://bugs.openjdk.java.net/browse/JDK-8243947
webrev: http://cr.openjdk.java.net/~ccheung/jdk15/8243947/webrev.00/

This change is to handle the situation when a JDK doesn't have default 
CDS archive or the CDS archive was created with a different vm options 
than the ones supplied for running the test. This change also address 
JDK-8243207: Increase AppCDS test coverage with ZGC.

Summary of changes:

- In DynamicArchiveTestBase.java, it checks if the UseSharedSpaces flag 
has been disabled using WhiteBox api. If so, it will regenerate a base 
CDS archive before running the dynamic CDS archive test.
- Since DynamicArchiveTestBase uses WhiteBox, all tests under 
dynamicArchive will need to be run with WhiteBox. Changes to the tests 
under dynamicArchive are mostly adding WhiteBox to the command line.
- In TestCommon.java, for AppCDS tests running with the 
-Dtest.dynamic.cds.archive=true option, a base CDS archive will be 
generated.

Testing:

     locally on linux-x64, ran appcds test group hotspot_appcds_dynamic 
with vmoptions="-Dtest.dynamic.cds.archive=true -XX:+UseZGC"
            and with the default CDS archive (classes.jsa) removed from 
the test JDK
     mach5 tier1 - 4.

thanks,

Calvin