[code-reflection] Integrated: Cleaned up NDRange and initialization of KernelBufferContext

[Gary Frost]

In preparing for specializomng kernel code based on Local dispatch dims I wanted to cleanup NDRange

Also simplify the initialization of KernelBufferContext  (removed mesh initialisation code)

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Commit messages:
 - Cleaned up NDRange and initialization of KernelBufferContext

Changes: https://git.openjdk.org/babylon/pull/729/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=729&range=00
  Stats: 216 lines in 5 files changed: 40 ins; 93 del; 83 mod
  Patch: https://git.openjdk.org/babylon/pull/729.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/729/head:pull/729

PR: https://git.openjdk.org/babylon/pull/729