RFR: 8339531: Improve performance of MemorySegment::mismatch

[Per Minborg]

This PR proposes to improve the performance of `MemorySegment::mismatch` by using Java code rather than transitioning to native code.

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Commit messages:
 - Remove temp methods
 - Clean up
 - Update comment
 - Merge branch 'master' into mismatch-performance2
 - Create a separate class for segment bulk operations
 - Add Java implementation of MS::mismatch

Changes: https://git.openjdk.org/jdk/pull/20848/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20848&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339531
  Stats: 267 lines in 4 files changed: 230 ins; 34 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/20848.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20848/head:pull/20848

PR: https://git.openjdk.org/jdk/pull/20848