[dynamo] Support control flow map() operator. (#91939)
Fixes #ISSUE_NUMBER
We want to add support for control flow map() at dynamo level to unblock some internal model which will have to use map() operator in captured graph. Basically I replicate the pattern for implementing cond() op from https://github.com/pytorch/pytorch/pull/90286
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91939
Approved by: https://github.com/ezyang
