[code-reflection] RFR: Lower SwitchExpressionOp [v4]

[Mourad Abbay]

> Lowering of SwitchExpressionOp

Mourad Abbay has updated the pull request incrementally with two additional commits since the last revision:

 - Generate lowered form that conforms to the JLS when selector expression is null
 - Refactor

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Changes:
  - all: https://git.openjdk.org/babylon/pull/45/files
  - new: https://git.openjdk.org/babylon/pull/45/files/c40d0e6e..896ca05b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=45&range=03
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=45&range=02-03

  Stats: 147 lines in 2 files changed: 101 ins; 27 del; 19 mod
  Patch: https://git.openjdk.org/babylon/pull/45.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/45/head:pull/45

PR: https://git.openjdk.org/babylon/pull/45