RFR: 8286: Fix broken launcher

[Marcus Hirt]

The launcher for launching JMC from within the development environment in Eclipse is broken. Going by features and adding some additional plug-ins solve it for me. Let me know if it works better for you too.

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Commit messages:
 - 8286: Fix launcher

Changes: https://git.openjdk.org/jmc/pull/601/files
  Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=601&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8286
  Stats: 88 lines in 1 file changed: 19 ins; 0 del; 69 mod
  Patch: https://git.openjdk.org/jmc/pull/601.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/601/head:pull/601

PR: https://git.openjdk.org/jmc/pull/601