Python function to extract information on mobile::Module from flatbuffer (#77624)
Summary:
Includes following refactor:
1. common loading on operator validation that is dup'd in pickle and
flatbuffer loader moved to function.h/cpp
2. Allow loading of a function without wiring operator.
This function will be used to implement get_bundled_input and friends
for flatbuffer.
Test Plan: contbuild & OSS CI, see https://hud.pytorch.org/commit/pytorch/pytorch/69fa49f1230f80d1a0667e0a6ac8aca2746431b6
Reviewed By: cccclai
Differential Revision: D36348549
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77624
Approved by: https://github.com/cccclai
