RFR: 8378203: Remove AppContext from jdk.unsupported.desktop

[Phil Race]

Remove AppContext from jdk.unsupported.desktop module

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Commit messages:
 - 8378203

Changes: https://git.openjdk.org/jdk/pull/29805/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29805&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378203
  Stats: 6 lines in 1 file changed: 0 ins; 4 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/29805.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29805/head:pull/29805

PR: https://git.openjdk.org/jdk/pull/29805