[code-reflection] Integrated: Added a Java code builder

[Gary Frost]

I have some tooling to visualize code models when converted to C99, I figured we should have one that converts bacl to java source. 

So fernflowery style. 

This is not in core but in the news tools project (where I plan on adding some of the more useful tools I have collected)

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Commit messages:
 - Added a Java code builder so we can show what a code model looks like when converted back to Java

Changes: https://git.openjdk.org/babylon/pull/487/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=487&range=00
  Stats: 30 lines in 8 files changed: 2 ins; 15 del; 13 mod
  Patch: https://git.openjdk.org/babylon/pull/487.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/487/head:pull/487

PR: https://git.openjdk.org/babylon/pull/487