[jdk11u-dev] RFR: 8306638: Open source some AWT tests related to datatransfer and Toolkit

[Goetz Lindenmaier]

I backport this for parity with 11.0.21-oracle.

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Commit messages:
 - Backport 2210e06788d14dab38f78d8b20a2397e633195af

Changes: https://git.openjdk.org/jdk11u-dev/pull/2027/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2027&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306638
  Stats: 863 lines in 5 files changed: 863 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2027.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2027/head:pull/2027

PR: https://git.openjdk.org/jdk11u-dev/pull/2027