Consolidate executor_runners

🚀 The feature, motivation and pitch

Now we have so many executor runner targets, one for each backend. We should use a main one, and the link backends.

If you look at https://github.com/search?q=repo%3Apytorch%2Fexecutorch+executor_runner+language%3ACMake&type=code&l=CMake you will see we have quite a few add_executable(xyz_executor_runner ...)

Often they contain the same source as the main executor runner: https://github.com/pytorch/executorch/blob/df8fc6102a598f4c0c7ffbcabe3c137d2d67ee5f/CMakeLists.txt#L765-L775

and the difference is they link to the different library.

In this code, we can see for XNNPACK, we can link to it

https://github.com/pytorch/executorch/blob/df8fc6102a598f4c0c7ffbcabe3c137d2d67ee5f/CMakeLists.txt#L786-L788

Just do the similar stuff for all backends

• qualcomm
• arm
• vulkan
• openvino
• mediatek
• coreml
• mps

After that, can we remove the extra xyz_executor_runner?

• qualcomm_
• arm_
• vulkan_
• openvino_
• mediatek_
• coreml_
• mps_
• xnnpack_

Alternatives

No response

Additional context

No response

RFC (Optional)

No response

cc @larryliu0820 @jathu

Start in CMakeLists.txt around the referenced executor_runner definitions and compare the main target with the XNNPACK linking example. Trace the executor runner targets for Qualcomm, Arm, Vulkan, OpenVINO, MediaTek, Core ML, MPS, and XNNPACK. Done means the backends use the consolidated runner where applicable and the listed extra targets can be removed.