RFR: 8349582: APX NDD code generation for OpenJDK [v4]

[Srinivas Vamsi Parasa]

> The goal of this PR is to generate code using APX NDD instructions.

Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:

  add flag(PD::...) and clean up loadNKlassCompactHeaders

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23501/files
  - new: https://git.openjdk.org/jdk/pull/23501/files/f09266d0..c578c936

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23501&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23501&range=02-03

  Stats: 81 lines in 1 file changed: 58 ins; 18 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/23501.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23501/head:pull/23501

PR: https://git.openjdk.org/jdk/pull/23501