[code-reflection] RFR: CoreOps to CoreOp, ExtendedOps to ExtendedOp [v4]

[Paul Sandoz]

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

Paul Sandoz has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:

 - Merge branch 'code-reflection' into top-type-ops
 - Doc update
 - Remove errant insert when refactoring
 - CoreOps to CoreOp, ExtendedOps to ExtendedOp

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Changes: https://git.openjdk.org/babylon/pull/73/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=73&range=03
  Stats: 1206 lines in 101 files changed: 66 ins; 38 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