Missing `test_bench` configuration support

[shink]

Seems --config is defined but not used actually in the test_bench userbenchmark. I would like to add support for it if this change makes sense.

benchmark/userbenchmark/test_bench/run.py

Lines 307 to 309 in 43851fb

	parser.add_argument(
	"--config", "-c", default=None, help="YAML config to specify tests to run."
	)

cc: @xuzhao9

[shink]

Actually, I'm working on a PyTorch out-of-tree test infra project, which is using torchbenchmark to test out-of-tree devices and can be found at here.
And we want to let each device vendor define their own configuration, might like this:

devices:
  - "foo"
models:
  - model: BERT_pytorch
    batch_size: 1

  - model: yolov3
    skip: true
extra_args:
  - "--accuracy"