[code-reflection] Integrated: Another step towards lowering Ptrs through SSA

[Gary Frost]

Another incremental step towards moving Ptrs down through SSA form. 

Still only support for loads and stores (no array access)

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Commit messages:
 - Another step towards lowering Ptrs through SSA

Changes: https://git.openjdk.org/babylon/pull/167/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=167&range=00
  Stats: 440 lines in 7 files changed: 178 ins; 114 del; 148 mod
  Patch: https://git.openjdk.org/babylon/pull/167.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/167/head:pull/167

PR: https://git.openjdk.org/babylon/pull/167