[code-reflection] RFR: Reduce number of local variables when transforming code model builder to AST

[Mourad Abbay]

For CODE_BUILDER option, we transform code model builder to equivalent AST. We were introducing local variables for very expressions, as a result we were closer to the limit on local variables. In this PR, we add local variables when it's needed.

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Commit messages:
 - Reduce number of local variables when transforming code model builder to AST

Changes: https://git.openjdk.org/babylon/pull/410/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=410&range=00
  Stats: 149 lines in 2 files changed: 93 ins; 24 del; 32 mod
  Patch: https://git.openjdk.org/babylon/pull/410.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/410/head:pull/410

PR: https://git.openjdk.org/babylon/pull/410