[WIP] CMake refactor

[GregoryComer]

Introduce a helper function to define an executorch runtime target.
Rename executorch_no_prim_ops to executorch_core.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/4710

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 3 New Failures, 1 Cancelled Job, 1 Unrelated Failure

As of commit f74050f with merge base dbd40f4 ():

NEW FAILURES - The following jobs have failed:

• Apple / build-frameworks-ios / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 1
• trunk / test-coreml-delegate / macos-job (gh)
  RuntimeError: Command bash /Users/runner/work/_temp/exec_script failed with exit code 1
• trunk / test-models-macos (cmake, vit, portable, macos-m1-stable, 90) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

CANCELLED JOB - The following job was cancelled. Please retry:

• trunk / test-models-macos (cmake, w2l, portable, macos-m1-stable, 90) / macos-job (gh)
  ##[error]The operation was canceled.

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• trunk / test-models-macos (cmake, emformer_transcribe, portable, macos-m1-stable, 90) / macos-job (gh) (matched macos rule in flaky-rules.json)
  File doesn't exist

This comment was automatically generated by Dr. CI and updates every 15 minutes.