[quant][graphmode][fx] Allow user to specify qconfig for call_method (#49621)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49621
This adds support to configure qconfig for a call_method, e.g. x.chunk, this will help workaround
a problem in our internal model.
TODO: since call_method is also a string and we flatten the qconfig, might need to resolve namespace conflict between
call_method and module_name
TODO: Add scope support to set the qconfig for call_method correctly with original qconfig
Test Plan: Imported from OSS
Reviewed By: vkuzo
Differential Revision: D25651828
fbshipit-source-id: 82d66b121d37c8274fd481b6a2e9f9b54c5ca73d
