[export] Fix serialization for auto_functionalization (#118810)
- Added support for serializig the auto_functionalization op, which
required adding the functions `serialize_arbitrary_inputs` and
`serialize_arbitrary_outputs` which will serialize the inputs/outputs
without needing a schema, since HOOs do not have a schema.
- Added support for serializing user input mutations
- Added support for serializing operator inputs. They just get turned
into strings.
Differential Revision: [D53331039](https://our.internmc.facebook.com/intern/diff/D53331039)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/118810
Approved by: https://github.com/suo
