RFR: 8336927: Missing equals and hashCode in java.lang.classfile.Annotation

[Chen Liang]

Convert `AnnotationImpl` to a record so it comes with proper `equals` and `hashCode` implementations. This also fixes the comparison for annotation-valued annotation element values.

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Commit messages:
 - 8336927: Missing equals and hashCode in java.lang.classfile.Annotation

Changes: https://git.openjdk.org/jdk/pull/20291/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20291&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336927
  Stats: 43 lines in 2 files changed: 23 ins; 14 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/20291.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20291/head:pull/20291

PR: https://git.openjdk.org/jdk/pull/20291