[Feature] Support BiSeNetV2 (#804)

* BiSeNetV2 first commit

* BiSeNetV2 unittest

* remove pytest

* add pytest module

* fix ConvModule input name

* fix pytest error

* fix unittest

* refactor

* BiSeNetV2 Refactory

* fix docstrings and add some small changes

* use_sigmoid=False

* fix potential bugs about upsampling

* Use ConvModule instead

* Use ConvModule instead

* fix typos

* fix typos

* fix typos

* discard nn.conv2d

* discard nn.conv2d

* discard nn.conv2d

* delete **kwargs

* uploading markdown and model

* final commit

* BiSeNetV2 adding Unittest for its modules

* BiSeNetV2 adding Unittest for its modules

* BiSeNetV2 adding Unittest for its modules

* BiSeNetV2 adding Unittest for its modules

* BiSeNetV2 adding Unittest for its modules

* BiSeNetV2 adding Unittest for its modules

* BiSeNetV2 adding Unittest for its modules

* Fix README conflict

* Fix unittest problem

* Fix unittest problem

* BiSeNetV2

* Fixing fps

* Fixing typpos

* bisenetv2