[lworld] RFR: 8294860: [lworld] Add java.util.Objects.isValueObject

[Roger Riggs]

Add method `java.util.Objects.isValueObject(Object obj)`.

The complement to `Objects.isIdentityObject(Object obj)` this method return true if the object is a value object.

Add the cases to the existing ObjectMethods test.

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

Commit messages:
 - 8294860: [lworld] Add java.util.Objects.isValueObject

Changes: https://git.openjdk.org/valhalla/pull/786/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=786&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294860
  Stats: 15 lines in 2 files changed: 15 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/786.diff
  Fetch: git fetch https://git.openjdk.org/valhalla pull/786/head:pull/786

PR: https://git.openjdk.org/valhalla/pull/786