RFR: 8250: Should show Resident Set Size

[Marcus Hirt]

Makes it easier to discover native leaks.

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Commit messages:
 - Formatting
 - Cleaning up a bit
 - Adding comment
 - Fixing copyright years
 - Adding RSS graphs

Changes: https://git.openjdk.org/jmc/pull/582/files
  Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=582&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8250
  Stats: 81 lines in 11 files changed: 58 ins; 11 del; 12 mod
  Patch: https://git.openjdk.org/jmc/pull/582.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/582/head:pull/582

PR: https://git.openjdk.org/jmc/pull/582