RFR: 8300682: InstanceKlassMiscStatus is a bad name

[Coleen Phillimore]

This patch is to simply rename InstanceKlassMiscStatus to InstanceKlassFlags.  This matches the naming for upcoming Field changes that add a FieldFlags class.
Tested with tier1-4.

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Commit messages:
 - 8300682: InstanceKlassMiscStatus is a bad name

Changes: https://git.openjdk.org/jdk/pull/12106/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12106&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300682
  Stats: 180 lines in 6 files changed: 69 ins; 69 del; 42 mod
  Patch: https://git.openjdk.org/jdk/pull/12106.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12106/head:pull/12106

PR: https://git.openjdk.org/jdk/pull/12106