[code-reflection] RFR: CoreOps to CoreOp, ExtendedOps to ExtendedOp

[Paul Sandoz]

Rename `CoreOps` to `CoreOp` and become the top-top for all core operations. Same for `ExtendedOps`.

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Commit messages:
 - CoreOps to CoreOp, ExtendedOps to ExtendedOp

Changes: https://git.openjdk.org/babylon/pull/73/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=73&range=00
  Stats: 1206 lines in 102 files changed: 67 ins; 37 del; 1102 mod
  Patch: https://git.openjdk.org/babylon/pull/73.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/73/head:pull/73

PR: https://git.openjdk.org/babylon/pull/73