[fx2trt] flatten converter (#62202)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62202

Add acc_ops.flatten converter. Also migrate to oss acc tacer for trt interpreter.

Test Plan: unit test

Reviewed By: khabinov

Differential Revision: D29861555

fbshipit-source-id: dac88a703fdbf386f3f7fb27674a67951f3add49
diff --git a/torch/fx/experimental/fx2trt/fx2trt.py b/torch/fx/experimental/fx2trt/fx2trt.py
index 9ad49e4..1cba2d3 100644
--- a/torch/fx/experimental/fx2trt/fx2trt.py
+++ b/torch/fx/experimental/fx2trt/fx2trt.py
@@ -288,4 +288,4 @@
             module = copy.deepcopy(module)
         module = module.cpu().float()
         module = NormalizeArgs(module).transform()
-        super().__init__(module, input_specs, logger_level)
+        super().__init__(module, input_specs, logger_level=logger_level)