equip etrecord class with save method (#13027)

This PR was created by the merge bot to help merge the original PR into
the main branch.
ghstack PR number: #12978 by
@Gasoonjia
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ghstack PR base:
https://github.com/pytorch/executorch/tree/gh/gasoonjia/29/base
ghstack PR head:
https://github.com/pytorch/executorch/tree/gh/gasoonjia/29/head
Merge bot PR base: https://github.com/pytorch/executorch/tree/main
Merge bot PR head:
https://github.com/pytorch/executorch/tree/gh/gasoonjia/29/orig
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Co-authored-by: gasoonjia <[email protected]>

Author: pytorchbot