Add run contexts and dynamo to E2E model trainer (#1123)
Summary:
Support torchdynamo for E2E model benchmarks and distributed.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1123
Reviewed By: wconstab
Differential Revision: D38847511
Pulled By: xuzhao9
fbshipit-source-id: c3777d95ae326e1145db9a38ef1ed1bfa438b684
