[quant][refactor] Change the structure of the ao migration tests (#64912)

[quant][refactor] Change the structure of the ao migration tests (#64912)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64912

The test naming was confusing and ambiguous. The file was changed to reflect the framework that is being migrated ("quantization" instead of "quantize"). Also, the common testing class was extracted out
ghstack-source-id: 138157450

Test Plan: `buck test mode/dev //caffe2/test:quantization -- TestAOMigrationQuantization`

Reviewed By: vkuzo

Differential Revision: D30898214

fbshipit-source-id: 017f95995271d35bcdf6ff6a1b3974b837543e84