RFR(M) JDK-8188791 Move AppCDS implementation from closed repo to open repo

[Ioi Lam]

Hi,

Please review this change set.

http://cr.openjdk.java.net/~iklam/jdk10/8188791-open-appcds-impl.v01/
     https://bugs.openjdk.java.net/browse/JDK-8188791

This is the first step of implementing the following JEP, which moves 
AppCDS from
closed repos into the openjdk repo:

     https://bugs.openjdk.java.net/browse/JDK-8185996

In JDK 9, significant portion of AppCDS code resided in the closed repo. 
As part
of the open-sourcing effort of JDK 18.3, we will move the source code 
into the
open repo.

In this changeset, the code is moved verbatim as much as possible. The 
intention is
only to relocate the sources, not to changing existing behaviors, and not
to do any sort of refactoring.

Most of the "diffs" shown in this webrev are the result of copying the 
closed source
files on top of files of the same name in the open repo. So in 
reviewing, instead of
focusing on what's "changed", it's better to focus on the entire content 
of the new
version of each file.

The only functional change in this task is that the UseAppCDS flag is 
changed from
a "commercial" flag to a regular "product" flag. This is because 
"commercial"
flags are not supported by the OpenJDK build.

Source code refactoring may be desirable, because the old open/closed source
code structure had introduced some intermediary APIs to connect code between
the two repos. Such API should be removed in a separate RFE.

Also, some AppCDS tests are currently in the closed repo. These tests 
will be
moved in a separate task. See JDK-8188792 for details.

All the AppCDS tests (currently still in closed sources) passed with 
both Oracle JDK
and OpenJDK.

Thanks
- Ioi