RFR: CODETOOLS-7903521: JOL: heapdumpstats should print array/class names properly

[Aleksey Shipilev]

Current "heapdumpstats" prints "Object[]" for all array types. It should print the actual type. Also, the printouts for the class names should be in more human-readable notation, not the JVM binary names.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jol/pull/45/files
 Webrev: https://webrevs.openjdk.org/?repo=jol&pr=45&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903521
  Stats: 141 lines in 3 files changed: 135 ins; 2 del; 4 mod
  Patch: https://git.openjdk.org/jol/pull/45.diff
  Fetch: git fetch https://git.openjdk.org/jol.git pull/45/head:pull/45

PR: https://git.openjdk.org/jol/pull/45