Allow to continue on error when installing `test_bench` (#2550)
Summary:
`test_bench` has many models, and sometimes we want to skip failed installations when installing them.
### Usage
```
python install.py --userbenchmark test_bench --continue_on_fail
```
### Result
```
$ python install.py --userbenchmark test_bench BERT_pytorch hf_GPT2 --skip hf_GPT2 --continue_on_fail
checking packages numpy, torch are installed, generating constaints...OK
Installing userbenchmark test_bench with extra args: []
Installing BERT_pytorch...OK
```
Pull Request resolved: https://github.com/pytorch/benchmark/pull/2550
Reviewed By: xuzhao9
Differential Revision: D66659907
Pulled By: FindHao
fbshipit-source-id: 90a97881daf8b0c95d9ddb39ff787ca665232260