replace Focus with Conv

[ljmiao]

It is recommended to replace Focus with conv, because Focus is extremely unfriendly to deployment, and doing so has almost no negative impact on the model, which has been confirmed in yolov5.
link: ultralytics/yolov5#4825

[FateScript]

Thanks, I will have try. I will inform you If anything updates.

[FateScript]

Using kernel_size 6x6 in Conv2d is not a good way to replace Focus. Anyway, since so many users are willing to replace Focus with Conv2d, we will try to do such a thing in a different way.

[scsolaris]

Using kernel_size 6x6 in Conv2d is not a good way to replace Focus. Anyway, since so many users are willing to replace Focus with Conv2d, we will try to do such a thing in a different way.

@FateScript any progress?