RFR: 8339902: Open source couple TextField related tests

[Alexander Zuev]

Clean up and open source five TextField related tests: 
java/awt/TextField/CaretPositionTest;
java/awt/TextField/SetBoundsTest;
java/awt/TextField/SetEchoCharTest4;
java/awt/TextField/SetPasswordTest;
java/awt/TextField/ZeroEchoCharTest

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Commit messages:
 - 8339902: Open source couple TextField related tests

Changes: https://git.openjdk.org/jdk/pull/21026/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21026&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339902
  Stats: 527 lines in 5 files changed: 527 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21026.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21026/head:pull/21026

PR: https://git.openjdk.org/jdk/pull/21026