RFR: 8306060: Open source few AWT Insets related tests

[Prasanta Sadhukhan]

This PR opensources few AWT Insets tests

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Commit messages:
 - 8306060: Open source few AWT Insets related tests

Changes: https://git.openjdk.org/jdk/pull/13552/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13552&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306060
  Stats: 270 lines in 4 files changed: 270 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13552.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13552/head:pull/13552

PR: https://git.openjdk.org/jdk/pull/13552