RFR: 8341162: Open source some of the AWT window test [v3]

[Jayathirth D V]

> Clean up and open source some of the AWT window tests.
> Automated test `OwnedWindowShowTest.java` is verified in our CI also and it passes on all platforms.

Jayathirth D V has updated the pull request incrementally with one additional commit since the last revision:

  Update based on review comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/21284/files
  - new: https://git.openjdk.org/jdk/pull/21284/files/f53ca0d1..38e5ab03

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21284&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21284&range=01-02

  Stats: 76 lines in 3 files changed: 26 ins; 36 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/21284.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21284/head:pull/21284

PR: https://git.openjdk.org/jdk/pull/21284