Vitaly Fedyunin

In addition to it, DLv2 should guarantee that `finalize` of `ReadingService` is called, even if Exception raised during iterations.

Please switch the order of inputs 'pattern' -> 'new name' looks more natural

In my opinion it makes sense to have two datapipes: `pattern_filter_keys` -> takes patterns, throws away all missmatch keys #406 and `pattern_rename_keys` -> takes pattern->new_name dictionary and renames keys accordingly....

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That's one of the options. Also requires join timeouts and errors propagation.

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We should put this information into the ReadingService interface file too. To make sure that RS developers know about potential deep copy.

One more though, we deepcopy RS, but we pickle-unpickle DP. I think we need to pick consistent approach.

Rebased, would be nice to land to clean torchdata's dependency tests.