RFR: 8341162: Open source some of the AWT window test [v4]

[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 for 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/38e5ab03..ac39165e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21284&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21284&range=02-03

  Stats: 32 lines in 3 files changed: 6 ins; 6 del; 20 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