[code-reflection] Integrated: Added hat nbody opengl example

[Gary Frost]

Here we have added HAT nbody implementation.  

It does require jextracted opengl and opencl (we can compare jextracted opencl and hat opencl).

hatrun updated to run nbody. 

Can't build nbody with maven yet.    


. ./env.bash
#We need to add jexract to PATH
export PATH=/Users/you/jextract-22/bin:${PATH}
java @bldr/bld 
java @bldr/hatrun opencl nbody

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Commit messages:
 - Added hat nbody opengl example

Changes: https://git.openjdk.org/babylon/pull/289/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=289&range=00
  Stats: 553 lines in 10 files changed: 535 ins; 13 del; 5 mod
  Patch: https://git.openjdk.org/babylon/pull/289.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/289/head:pull/289

PR: https://git.openjdk.org/babylon/pull/289