[FX] Rename Node._uses and refactor Node.all_input_nodes (#49415)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/49415
Test Plan: Imported from OSS
Reviewed By: zdevito
Differential Revision: D25565341
Pulled By: jamesr66a
fbshipit-source-id: 2290ab62572632788809ba16319578bf0c0260ee
