RFR: 8368475: [lworld] Add preview classes to jimage at make time

[David Beaumont]

Copies valuetype classes for each module into corresponding "/META-INF/preview/..." sub-directories to be pulled into jimage files and processed by the new preview mode handling code.

There might be a better way to do this in terms of Makefile semantics, but this seems to work well enough and doesn't prevent the value-class JAR files being generated for patching (which is still how everyone will get value classes until the rest of the work is plumbed in).

To enable the new preview mode work, set the "DISABLE_PREVIEW_PATCHING" system property to "true".

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Depends on: https://git.openjdk.org/valhalla/pull/1718

Commit messages:
 - Rollup of makefile change and jlink fix (temp).
 - [[AUTOMATIC FORMATTING]]
 - fixing tests after refactoring
 - Fixing up after dependent PR changes
 - feedback and remove unused code
 - [[AUTOMATIC FORMATTING]]
 - new tests for ImageLocation
 - Restoring lost changes and updating some comments.
 - add system property guard to preview mode
 - Remove TODOs now jimage version is bumped
 - ... and 1 more: https://git.openjdk.org/valhalla/compare/a6d6cb8b...14f2a490

Changes: https://git.openjdk.org/valhalla/pull/1719/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1719&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8368475
  Stats: 3595 lines in 39 files changed: 1306 ins; 391 del; 1898 mod
  Patch: https://git.openjdk.org/valhalla/pull/1719.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1719/head:pull/1719

PR: https://git.openjdk.org/valhalla/pull/1719