[pruner] add getter for pruned outputs in base pruner (#63520)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63520
Rather than having to call `module.parametrizations.weight[0].pruned_outputs` each time we need to access the set of pruned indices, we add a getter `get_module_pruned_outputs` which takes the module as an argument and returns the set.
This is used for testing.
ghstack-source-id: 136561130
Test Plan:
` buck test mode/dev-nosan //caffe2/test:ao -- TestBasePruner`
https://pxl.cl/1N4gK
Reviewed By: z-a-f
Differential Revision: D30374558
fbshipit-source-id: e38dfee0879cadde52b942e899a3d8d7151ee493
