[code-reflection] RFR: Detect if a java switch is case constant

[Mourad Abbay]

Add the logic to check if a switch op is case constant.

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Commit messages:
 - Detect if a java switch is case constant

Changes: https://git.openjdk.org/babylon/pull/710/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=710&range=00
  Stats: 224 lines in 2 files changed: 224 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/babylon/pull/710.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/710/head:pull/710

PR: https://git.openjdk.org/babylon/pull/710