RFR: 8306135: Clean up and open source some AWT tests [v3]

[Alexander Zuev]

> Cleaning up and open sourcing three AWT tests

Alexander Zuev has updated the pull request incrementally with one additional commit since the last revision:

  Splitting couple of extra long lines to keep it more readable

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13518/files
  - new: https://git.openjdk.org/jdk/pull/13518/files/8877ee01..2a04dffa

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13518&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13518&range=01-02

  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13518.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13518/head:pull/13518

PR: https://git.openjdk.org/jdk/pull/13518