[ExecuTorch][to_backend] Introduce preprocess_all method to backend details #9810
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Stack from ghstack (oldest at bottom):
We introduce the new static method preprocess_all. This is not an enforced method because preprocess() is enforced and can be used instead.
Ideally, I want the default implementation of preprocess_all, to just loop through the exported programs for each method and use preprocess() to lower them. However since each are static methods, I wasn't able to find a good way to do this. Suggestions would be greatly appreciated for that.
Differential Revision: D69954544