[code-reflection] Integrated: added a nbody vector kernel

[Gary Frost]

An initial attempt at vector nbody kernel (using Float4 vector types) - Needs some array view help

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Commit messages:
 - added a nbody vector kernel

Changes: https://git.openjdk.org/babylon/pull/701/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=701&range=00
  Stats: 57 lines in 3 files changed: 53 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/babylon/pull/701.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/701/head:pull/701

PR: https://git.openjdk.org/babylon/pull/701