Make all executors execute tier 2 instructions (micro-ops)

[markshannon]

Our plan proposes that we either execute all tier 2 code in the tier 2 interpreter or by jitting the code

However, our current executor interface allows calls to arbitrary function pointers.
We should remove that interface, requiring all optimizers to produce tier 2 micro-ops, which the VM is responsible for executing.

This will prevent low-level JITs like Cinder from using executors, but Cinder uses PyFunction_SetVectorcall to insert machine code anyway.
Higher level JITs like PyTorch dynamo, can potentially still use executors, as they provide a more powerful and flexible interface than PEP 523.

Linked PRs

• GH-113860: All executors are now defined in terms of micro ops. Convert counter executor to use uops. #113864
• GH-113860: Get rid of _PyUOpExecutorObject #113954

[erlend-aasland]

Is there more work left to do?

[markshannon]

Nope