[code-reflection] RFR: Add kernel entrypoint to ModuleOp

[Ruby Chen]

Include the kernel (and compute) entrypoints in their respective ModuleOps.

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Commit messages:
 - Add kernel entrypoint to ModuleOp

Changes: https://git.openjdk.org/babylon/pull/605/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=605&range=00
  Stats: 43 lines in 2 files changed: 9 ins; 22 del; 12 mod
  Patch: https://git.openjdk.org/babylon/pull/605.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/605/head:pull/605

PR: https://git.openjdk.org/babylon/pull/605