[code-reflection] RFR: Concat Transform Optimizations [v5]

[Ian Graves]

> Updates to the transformation on Concats to StringBuilder that reduce redundant "new" StringBuilders while respecting correctness.

Ian Graves has updated the pull request incrementally with one additional commit since the last revision:

  Renaming some tests and adding additional coverage for side-effects in StringBuilder

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Changes:
  - all: https://git.openjdk.org/babylon/pull/149/files
  - new: https://git.openjdk.org/babylon/pull/149/files/7d966a45..b38af670

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=149&range=04
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=149&range=03-04

  Stats: 46 lines in 1 file changed: 40 ins; 2 del; 4 mod
  Patch: https://git.openjdk.org/babylon/pull/149.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/149/head:pull/149

PR: https://git.openjdk.org/babylon/pull/149