RFR: CODETOOLS-7903522: JOL: Heap dump readers should print progress

[Aleksey Shipilev]

For large heap dumps, it would be convenient to see the read progress.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jol/pull/46/files
 Webrev: https://webrevs.openjdk.org/?repo=jol&pr=46&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903522
  Stats: 31 lines in 5 files changed: 18 ins; 7 del; 6 mod
  Patch: https://git.openjdk.org/jol/pull/46.diff
  Fetch: git fetch https://git.openjdk.org/jol.git pull/46/head:pull/46

PR: https://git.openjdk.org/jol/pull/46