RFR: 8316149: Open source several Swing JTree JViewport KeyboardManager tests

[Damon Nguyen]

These are the tests being converted:

javax/swing/JTree/4696499/bug4696499.java
javax/swing/JTree/5039542/bug5039542.java
javax/swing/JViewport/4546474/bug4546474.java
javax/swing/JViewport/4677611/bug4677611.java
javax/swing/KeyboardManager/4345798/bug4345798.java

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Commit messages:
 - Initial test conversion to open

Changes: https://git.openjdk.org/jdk/pull/15802/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15802&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316149
  Stats: 434 lines in 5 files changed: 434 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15802.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15802/head:pull/15802

PR: https://git.openjdk.org/jdk/pull/15802