Add typical GNN workloads (#1422)
Summary:
This PR is to add typical GNN workloads which is one task in https://github.com/pytorch/benchmark/issues/1293.
This task includes:
- Add models in `torchbenchmark`: including `GCN`, `GraphSage` and `GAT`.
- Use real datasets as inputs: Split subgraph from `Reddit`.
- Add metrics
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1422
Reviewed By: weiwangmeta
Differential Revision: D43946504
Pulled By: xuzhao9
fbshipit-source-id: 6e979ed871c2d3bffa16ca1c6b713d71f56bb7e3
