Support ADE20k for semantic segmentation with deeplabv3+

[CoinCheung]

🚀 Feature

Support ADE20k for semantic segmentation with deeplabv3+

Motivation & Examples

This will be helpful when people need to benchmark different self-supervised learning method, since most ssl paper do experiments on ade20k semantic segmantation dataset.

For example: the repo of moco uses detectron2 to do experiments on downstream task of object detection, but it lacks semantic segmantation experiments. Maybe it is because detectron2 does not support it directly and explicitly.

[tungts1101]

Is there any progress on this issue? I found the documentation on registering datasets is really poor without any example of registering ade20k for the semantic segmentation task.