RFR: 8071: Cleanup after latest refactorings

Tue May 23 22:17:02 UTC 2023

After JMC-7308, test JVMCommandLineToolkitTest.java should move into core/common.
Also, there are some Javadoc related warnings during core build which should be fixed.

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Commit messages:
 - JMC-8071

Changes: https://git.openjdk.org/jmc/pull/485/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=485&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8071
  Stats: 39 lines in 4 files changed: 3 ins; 10 del; 26 mod
  Patch: https://git.openjdk.org/jmc/pull/485.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/485/head:pull/485

PR: https://git.openjdk.org/jmc/pull/485