[code-reflection] Integrated: We can now build jextracted artifacts from maven

[Gary Frost]

Previously maven coould not extract opencl/opengl or cuda.  Mainly because I had no idea how to get maven to 'generate code' and then build. 

I moved the cmake invoke  from each subdir `extractions/[cuda|opencl|opnegl]/pom.xml` to the common parent and finally discovered how to get each child pom to not duplicate the build. 

So now 

mvn -e clean compile package install -Popencl,opengl


And 


java @hat/bld 


Create the same artifacts

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Commit messages:
 - We can now build jextracted artifacts from maven

Changes: https://git.openjdk.org/babylon/pull/484/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=484&range=00
  Stats: 1620 lines in 17 files changed: 44 ins; 1502 del; 74 mod
  Patch: https://git.openjdk.org/babylon/pull/484.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/484/head:pull/484

PR: https://git.openjdk.org/babylon/pull/484