[~utils.BackboneMixin] enables initializing a backbone from Transformers or timm and includes functions for returning the output features and indices.
[~utils.BackboneConfigMixin] sets the output features and indices of the backbone configuration.

timm models are loaded with the [TimmBackbone] and [TimmBackboneConfig] classes.
Backbones are supported for the following models:

BEiT
BiT
ConvNet
ConvNextV2
DiNAT
DINOV2
FocalNet
MaskFormer
NAT
ResNet
Swin Transformer
Swin Transformer v2
ViTDet