[caffe2] add a SerializationOptions field for the save operator (#53402)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53402
Add an `options` field to the `Save` operator which accepts options for how to
serialize different blobs. At the moment this simply allows controlling the
existing `chunk_size` behavior, but in the future we can add other options,
such as the ability to control compression settings or other serialization
formats.
ghstack-source-id: 123567034
Test Plan:
Added a new test to `load_save_test.py` that passes in options and verifies
that blobs were serialized with the expected number of chunks.
buck test caffe2/caffe2:caffe2_test_cpu \
caffe2/caffe2/core:serialization_test \
caffe2/caffe2/python/operator_test:load_save_test
Reviewed By: mraway
Differential Revision: D26502577
fbshipit-source-id: 6e302e530bb96990517c2e35c505db7f14a56284
