Samsung Exynos: Refactor such that python extensions are installed via setup.py

[mergennachin]

Follow-up to this comment: https://github.com/pytorch/executorch/pull/13677/files#r2302174145

Refactor such that python extensions are installed via setup.py

cc @SS-JIA @Jiseong-oh @digantdesai @kimishpatel

[Jiseong-oh]

Could you let us know what is the pr? we will figure out about that.