RFR: 8306996: Open source Swing MenuItem related tests

[Abhishek Kumar]

This PR is to open source JMenuItem related swing tests.

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Commit messages:
 - Open Source Swing JMenuItem Tests

Changes: https://git.openjdk.org/jdk/pull/13822/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13822&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306996
  Stats: 447 lines in 4 files changed: 447 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13822.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13822/head:pull/13822

PR: https://git.openjdk.org/jdk/pull/13822