RFR: 7096: Bring back Object statistics table for heap.

[Virag Purnam]

In the memory page, below mentioned columns have been added as per the request from customer. These columns are not visible by default. Users can select these from "Visible Columns" option. Customer wants these columns for the "Object Statistics". 

- Avg Live Count
- Avg Live Size
- Live Instances Increase
- Percentage of Heap

![ObjectStatistics](https://user-images.githubusercontent.com/97600378/186091512-b434560a-96b1-4e62-80b8-029ae95169bf.jpg)

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Commit messages:
 - 7096: Bring back Object statistics table for heap.

Changes: https://git.openjdk.org/jmc/pull/420/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=420&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-7096
  Stats: 71 lines in 9 files changed: 69 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jmc/pull/420.diff
  Fetch: git fetch https://git.openjdk.org/jmc pull/420/head:pull/420

PR: https://git.openjdk.org/jmc/pull/420