[Feature] Support ICNet (#884)

* add icnet backbone

* add icnet head

* add icnet configs

* nclass -> num_classes

* Support ICNet

* ICNet

* ICNet

* Add ICNeck

* Add ICNeck

* Add ICNeck

* Add ICNeck

* Adding unittest

* Uploading models & logs

* Uploading models & logs

* add comment

* smaller test_swin.py

* try to delete test_swin.py

* delete test_unet.py

* delete test_unet.py

* temp

* smaller test_unet.py

Co-authored-by: Junjun2016 <hejunjun@sjtu.edu.cn>