RFR: 7903806: Enhance jasm/jdis to support value classes and objects

[Dan Smith]

Some changes to align Valhalla support in asmtools with the latest design for JEP 401.

Latest JVM specification can be found here: https://cr.openjdk.org/~dlsmith/jep401/jep401-20240624/specs/value-objects-jvms.html

I originally made these changes on a custom copy of asmtools, so this was mostly a matter of reviewing my original patch and making updates. There have been some changes, though, and it's quite possible I've missed something.

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Commit messages:
 - 7903806: Enhance jasm/jdis to support value classes and objects

Changes: https://git.openjdk.org/asmtools/pull/73/files
  Webrev: https://webrevs.openjdk.org/?repo=asmtools&pr=73&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903806
  Stats: 380 lines in 16 files changed: 198 ins; 114 del; 68 mod
  Patch: https://git.openjdk.org/asmtools/pull/73.diff
  Fetch: git fetch https://git.openjdk.org/asmtools.git pull/73/head:pull/73

PR: https://git.openjdk.org/asmtools/pull/73