RFR: 8283607: Rename KlassID to KlassKind

[Stefan Karlsson]

During the review of JDK-8283574 / #7922 , it was brought up that the term ID to describe the "kind" of *Klass is misleading. Rename KlassID to KlassKind, and update names of variables of KlassID.

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Commit messages:
 - 8283607: Rename KlassID to KlassKind

Changes: https://git.openjdk.java.net/jdk/pull/7936/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7936&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283607
  Stats: 62 lines in 14 files changed: 2 ins; 0 del; 60 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7936.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7936/head:pull/7936

PR: https://git.openjdk.java.net/jdk/pull/7936