[Feature] Adding 'CascadeRCNN in the models registry

[Vinay07Vallala]

What is the feature?

Adding CascadeRCNN in the models registry

Any other context?

Error : 'CascadeRCNN is not in the models registry' getting this error when I try to load a config from model

below image has the snippet of the config

code

import mmcv
cfg = mmcv.Config.fromfile(config)