[export] Add schema version to serializer/deserializer (#107420)
Added a version number to the schema for BC issues. We will add this number to the serialized ExportedProgram and then when deserializing, if the number does not match up with the existing deserializer, we will error. We should update the number of there are any major changes to the schema.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107420
Approved by: https://github.com/zhxchen17
