[code-reflection] RFR: Remove CodeElement.transform [v2]

[Paul Sandoz]

> Remove the `CodeElement.transform` method and the helper methods. Traversal of elements is performed using the `CodeElement.elements` method that returns a stream of code elements.

Paul Sandoz has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/code-reflection' into rm-ce-transform
 - Remove comments.
 - Merge remote-tracking branch 'upstream/code-reflection' into rm-ce-transform
 - Remove CodeElement.transform method.

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Changes:
  - all: https://git.openjdk.org/babylon/pull/737/files
  - new: https://git.openjdk.org/babylon/pull/737/files/d4c3bb54..6d5444ec

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=737&range=01
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=737&range=00-01

  Stats: 600 lines in 59 files changed: 217 ins; 78 del; 305 mod
  Patch: https://git.openjdk.org/babylon/pull/737.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/737/head:pull/737

PR: https://git.openjdk.org/babylon/pull/737