[Feature Request] Add support for YoloFastest

[aychun]

• I have searched to see if a similar issue already exists.

Is there any feature that you would like to add?
Add support for the YOLO Fastest model

Is there any suggestion (or solution) to solve this issue?

• Add required model components
• Add required postprocessers and loss functions
• Add required configuration setups
  • Add documentations regarding new configurations

[hglee98]

There are some technical issues to implement the full model and make sure the model running correctly..
Therefore, is it okay for me to implement YOLOFastestV2 from scratch and raise a PR first? @illian01 @aychun
I think It will be easier to revisit the YOLOFastestV1 when I finish the work and get back to it.