[code-reflection] Integrated: Improve coverage of JavaCodeBuilder and moved to optkl

[Gary Frost]

Finally untangled JavaCodeBuilder from it's earlier C99 code builder heritage. 

Now it can be used outside of hat. 

It's getting better, but still needs to cover more cases.

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Commit messages:
 - Moved JavaCodeBuilder to optkl
 - Improve JavaHATCodeBuilder

Changes: https://git.openjdk.org/babylon/pull/817/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=817&range=00
  Stats: 2185 lines in 20 files changed: 1050 ins; 1000 del; 135 mod
  Patch: https://git.openjdk.org/babylon/pull/817.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/817/head:pull/817

PR: https://git.openjdk.org/babylon/pull/817