Support `import lldb` in a Python interpreter that's different from the one we link against

When building LLDB agains the Python Limited C ABI [1], it should be possible to do `import lldb` in a Python interpreter that isn't the same version as the one we built and link against.

- [x] [Make LLDB compatible with the Python Limited C API](https://github.com/llvm/llvm-project/issues/151617)
- [x] [Support a Stable ABI LLDB_PYTHON_EXT_SUFFIX](https://github.com/llvm/llvm-project/pull/166269)
- [ ] [Fix crash in `_PyObject_Malloc`](https://github.com/llvm/llvm-project/issues/167002)

[1] https://github.com/llvm/llvm-project/issues/151617