Consolidate all python targets in the tools folder (#80408)
Summary:
All buck targets that points to caffe2/tools folder are now moved to tools/BUCK.
This also eliminates all python library/binary import in pt_defs.bzl, which caused T124308913.
Test Plan: CI
Differential Revision: D37468313
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80408
Approved by: https://github.com/seemethere, https://github.com/malfet
