RFR: 8312623: SA add NestHost and NestMembers attributes when dumping class

[Ashutosh Mehra]

This patch adds NestHost and NestMembers attributes to the class dumped by SA.

Testing: `test/hotspot/jtreg/serviceability/sa` and `test/jdk/sun/tools/jhsdb`
Manual testing by dumping `j.l.String` and `j.l.String$CaseInsensitiveComparator` classes.
`j.l.String` shows one entry in `NestMembers` attribute for `j.l.String$CaseInsensitiveComparator` and `j.l.String$CaseInsensitiveComparator` has `j.l.String` as its `NestHost`.

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Commit messages:
 - 8312623: SA add NestHost and NestMembers attributes when dumping class

Changes: https://git.openjdk.org/jdk/pull/15005/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15005&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312623
  Stats: 50 lines in 3 files changed: 50 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15005.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15005/head:pull/15005

PR: https://git.openjdk.org/jdk/pull/15005