[lworld] RFR: 8260606: Update Valhalla core-libs naming for methods related to primitive classes

[Roger Riggs]

Update terminology used to refer to primitive classes (from inline classes).
Drop the descriptions using "projection" and use "conversion" as needed.
Updated dependencies on Class.isPrimitiveClass().

[Updating test names will be a separate task.]

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Commit messages:
 - 8260606: Update Valhalla core-libs naming for methods related to primitive classes

Changes: https://git.openjdk.java.net/valhalla/pull/318/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=318&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260606
  Stats: 206 lines in 28 files changed: 0 ins; 14 del; 192 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/318.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/318/head:pull/318

PR: https://git.openjdk.java.net/valhalla/pull/318