[lworld] RFR: 8287692: Move Class primitive APIs to jdk.internal.value

[Roger Riggs]

To avoid confusion with the reflection support for [Value Objects](https://bugs.openjdk.java.net/browse/JDK-8277163)
the java.lang.Class APIs in support of JEP 401 (Primitive Objects) should be hidden.

The methods `Class.asValueType`, `asPrimaryType`, `isPrimaryType`, `isPrimitiveClass`, and `asPrimitiveValueType`
are moved to be static methods of `jdk.internal.value.PrimitiveClass`.

To access those methods, add `--exports java.base/jdk.internal.value:+open` to the command line
in addition to other flags needed to enable Primitive Objects and convert to invoke them as static methods with the class.

The openjdk classes and tests are modified to use the alternate API.

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

Commit messages:
 - 8287692-only-value-classes: Move Class primitive APIs to jdk.internal.value.

Changes: https://git.openjdk.java.net/valhalla/pull/704/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=704&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8287692
  Stats: 526 lines in 58 files changed: 274 ins; 28 del; 224 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/704.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/704/head:pull/704

PR: https://git.openjdk.java.net/valhalla/pull/704