RFR: JDK-8353201 : Open source Swing Tooltip tests - Set 2

[Harshitha Onkar]

Open sourced the following ToolTipManager tests-

- javax/swing/ToolTipManager/bug4250178.java
- javax/swing/ToolTipManager/bug4294808.java
- javax/swing/ToolTipManager/bug6178004.java

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Commit messages:
 - Tooltip sets

Changes: https://git.openjdk.org/jdk/pull/24453/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24453&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8353201
  Stats: 282 lines in 3 files changed: 282 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24453.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24453/head:pull/24453

PR: https://git.openjdk.org/jdk/pull/24453