[lworld] RFR: 8336028: [lworld] Serialization should throw exceptions for non-migrated value classes

[Roger Riggs]

The java.base classes being migrated to value classes when using --enable-preview use a temporary adhoc unsafe mechanism to be serialized and deserialized. Only classes that are annotated with `jdk.internal.MigratedValueClass` can be serialized and deserialized. All other value classes can not be serialized or deserialized and the respective APIs throw exceptions. Subsequent Valhalla work will provide the missing support.

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Commit messages:
 - 8336028: [lworld] Serialization should throw exceptions for non-migrated value classes

Changes: https://git.openjdk.org/valhalla/pull/1164/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1164&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336028
  Stats: 25 lines in 5 files changed: 16 ins; 3 del; 6 mod
  Patch: https://git.openjdk.org/valhalla/pull/1164.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1164/head:pull/1164

PR: https://git.openjdk.org/valhalla/pull/1164