[Static Runtime] [Code Cleanup] Encapsulate function objects within ProcessedFunction (#69595)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/69595
This changes encapsulates `function` object in `ProcessedFunction` objects instead of exposing it unnecessarily just for executing it.
Test Plan: Existing tests
Reviewed By: mikeiovine
Differential Revision: D32908341
fbshipit-source-id: 5ff4951cbe276c5c6292227124d9eec1dd16e364
