[FX] make visualizer produce different formatted output (#64699)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64699
Previously we just hardcode to svg format. We should give folks a choice in terms of what format they want to see. If we give a weird extension like .abc and this will error out and we expect this to be the right behavior.
Reviewed By: houseroad
Differential Revision: D30718883
fbshipit-source-id: fe8827262f94ea6887999bb225de763d1909eef8
