Remove dependency from torch gitsubmodule Part 1/N (#3538)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/3538

In this diff, I am removing external third-party library called "gen-oplist-lib" altogether from core.

For the time being, I am just copying over that one file but looks like we can simplify a lot of code there in the future.

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Reviewed By: larryliu0820

Differential Revision: D57078472

fbshipit-source-id: ac8d8d7051f077980e2aa443a7a020b9a9711950