[lworld] RFR: 8366093: [lworld] Add preview mode to ImageReader and JRT file-system [v2]

[David Beaumont]

> Java changes for supporting preview mode when preview mode resources (with new location flags) are available.
> 
> At the moment, this code will operate on non-preview jimage files (1.0) and act as if no preview resources are available by virtue of the default value for missing attributes and package flags being zero (which matches jimage 1.0).
> 
> Compare and review this against https://github.com/openjdk/valhalla/pull/1609.
> 
> https://github.com/openjdk/valhalla/pull/1613/files/4e21d5e00ac05d4197e8c617dbabec84ce8748f9..c23b8f25e943000b1aebeaf0755599a9c17b4a91

David Beaumont has updated the pull request incrementally with one additional commit since the last revision:

  Add workaround until new image writing code is in

-------------

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1613/files
  - new: https://git.openjdk.org/valhalla/pull/1613/files/c23b8f25..41ba71bf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1613&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1613&range=00-01

  Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1613.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1613/head:pull/1613

PR: https://git.openjdk.org/valhalla/pull/1613