[code-reflection] Integrated: Seal NDRange interfaces anc simplify HATThreadOp and phases

[Gary Frost]

Sealed the NDRange (Local/Global) interface heirarchy.  This helps in pattern switching.

Also simpified the various HATThreadOp's .  They all had common fields (name, resultType) so I pushed these down to the base HATThreadOp class.

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Commit messages:
 - Seal NDRange interfaces anc simplify HATThreadOp and phases

Changes: https://git.openjdk.org/babylon/pull/775/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=775&range=00
  Stats: 248 lines in 9 files changed: 72 ins; 107 del; 69 mod
  Patch: https://git.openjdk.org/babylon/pull/775.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/775/head:pull/775

PR: https://git.openjdk.org/babylon/pull/775