bazel_gomock ignores mockgen_args in archive mode

(Template removed for brevity)

The patch that added bazel_gomock ~3wk ago removed the ability to pass mockgen_args: https://github.com/uber-go/mock/commit/aa11bfcd02f7339576f4cef5b8c697f980f607d2#diff-3747455c98c2da6a894f54e5710a88bdf045ff5f5ea4ff855265b1d9b64dd376L225

I think this was unintentional.