RFR: 8339168: Optimize ClassFile Util slotSize [v6]

[Shaojin Wen]

> A small optimization to improve the performance of jdk.internal.classfile.impl.Util#slotSize/isDoubleSlot

Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into optim_util_slotSize_20240828
 - Merge remote-tracking branch 'upstream/master' into optim_util_slotSize_20240828
 - suggestion from @cl4es
 - add benchmark
 - suggestion from @liach & @cl4es
 - Suggestions from @cl4es
 - optimize slotSize & isDoubleSlot

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20747/files
  - new: https://git.openjdk.org/jdk/pull/20747/files/972ba60d..550216ab

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20747&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20747&range=04-05

  Stats: 12812 lines in 445 files changed: 7859 ins; 2260 del; 2693 mod
  Patch: https://git.openjdk.org/jdk/pull/20747.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20747/head:pull/20747

PR: https://git.openjdk.org/jdk/pull/20747