RFR: 8353655: Clean up and open source KeyEvent related tests (Part 1) [v2]

[Alexander Zuev]

> Clean up and open source three tests related to the KeyEvent mechanics.

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

  Small fixes based on review comments

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24609/files
  - new: https://git.openjdk.org/jdk/pull/24609/files/af6ca77b..b8761634

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24609&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24609&range=00-01

  Stats: 6 lines in 3 files changed: 1 ins; 3 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24609.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24609/head:pull/24609

PR: https://git.openjdk.org/jdk/pull/24609