Add NamedData to flat_tensor schema (#9571)

This PR was created by the merge bot to help merge the original PR into
the main branch.
ghstack PR number: https://github.com/pytorch/executorch/pull/9123 by
@lucylq
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ghstack PR base:
https://github.com/pytorch/executorch/tree/gh/lucylq/57/base
ghstack PR head:
https://github.com/pytorch/executorch/tree/gh/lucylq/57/head
Merge bot PR base: https://github.com/pytorch/executorch/tree/main
Merge bot PR head:
https://github.com/pytorch/executorch/tree/gh/lucylq/57/orig
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Co-authored-by: lucylq <lfq@meta.com>