RFR: 7903711: Rewrite simple methods ANC plugin to classfile API

[Alexandre Iline]

Rewritten using JDK 22.

openjdk.jcov.filter.simplemethods.InstructionIterator make the code a lot simpler.

No change needed to tests, except to change from ASM ClassNode to ClassModel from the classfile API

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Commit messages:
 - CODETOOLS-7903711: Rewrite simple methods ANC plugin to classfile API

Changes: https://git.openjdk.org/jcov/pull/44/files
  Webrev: https://webrevs.openjdk.org/?repo=jcov&pr=44&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903711
  Stats: 360 lines in 15 files changed: 82 ins; 134 del; 144 mod
  Patch: https://git.openjdk.org/jcov/pull/44.diff
  Fetch: git fetch https://git.openjdk.org/jcov.git pull/44/head:pull/44

PR: https://git.openjdk.org/jcov/pull/44