Add `MLIR_ENABLE_PYTHON_STABLE_ABI` cmake flag to build bindings against
the Python limited/stable API (abi3 / PEP 384). This allow for
compatibility across different >=3.12 versions with a single .so /
wheel. We also require CMake >=3.26.
The stable ABI restricts usage to a subset of the CPython C API: frame
and code object structs are opaque, so introspection APIs like
`PyCode_Addr2Location`, `PyFrame_GetLasti`, and `PyFrame_GetCode` are
unavailable. The traceback-based auto-location logic is dropped because
we don’t have stable ABI to produce complete locations.
Assisted-by: claude
2c9720972e