[lworld] RFR: JDK-8251986: [lworld] implement Class::valueType and Class::referenceType in Java [v2]

[Mandy Chung]

> Now that javac generates the reference projection class as a sealed type,
> this patch reimplements  `Class::valueType` and `Class::referenceType` in Java.
> VM no longer has any knowledge of the value projection type and reference projection type.
> 
> This patch includes a temporary workaround to disable the preview feature check
> for sealed types because inline types are not (yet) a preview feature in valhalla repo.
> This workaround should be removed when it's time to make inline class a preview feature.

Mandy Chung has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev
excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since
the last revision:

 - remove debug println statement
 - Merge branch 'lworld' of https://github.com/openjdk/valhalla into projection-types
 - supports_sealed_types checks only the major version
 - remove unused import
 - disable preview feature check for sealed types
 - Merge branch 'lworld' of https://github.com/openjdk/valhalla into lworld
 - implement Class::referenceType and Class::valueType in Java

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

Changes:
  - all: https://git.openjdk.java.net/valhalla/pull/152/files
  - new: https://git.openjdk.java.net/valhalla/pull/152/files/65d3cc87..36d4d860

Webrevs:
 - full: https://webrevs.openjdk.java.net/valhalla/152/webrev.01
 - incr: https://webrevs.openjdk.java.net/valhalla/152/webrev.00-01

  Stats: 528 lines in 23 files changed: 327 ins; 49 del; 152 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/152.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/152/head:pull/152

PR: https://git.openjdk.java.net/valhalla/pull/152