add an interpolate_embeddings helper function

[DanTaranis]

This library is awesome. However I want to pretrain on small patches and then transfer learn on larger images. torchvision has a really great helper function for their vision transformer class : interpolate_embeddings.

"""This function helps interpolating positional embeddings during checkpoint loading,
    especially when you want to apply a pre-trained model on images with different resolution.

it would be awesome if your library also had something like that :)