RFR: JDK-8328753 : Open source few Undecorated Frame tests

[Harshitha Onkar]

Following tests are converted to main and open-sourced:

- /java/awt/Frame/FrameDialogMixedTest.java- Converted to main/manual using PassFailJFrame.
- /java/awt/Frame/MaximizeUndecoratedTest.java - Automated
- /java/awt/Frame/MinimizeUndecoratedTest.java - Automated

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Commit messages:
 - spacing
 - Undecorated Frame tests added

Changes: https://git.openjdk.org/jdk/pull/18523/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18523&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328753
  Stats: 350 lines in 3 files changed: 350 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18523.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18523/head:pull/18523

PR: https://git.openjdk.org/jdk/pull/18523