Python function to extract information on mobile::Module from flatbuffer (#77328)
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.
Fixes #ISSUE_NUMBER
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77328
Approved by: https://github.com/cccclai
