Support for FastViT

[awsaf49]

Apple recently released their model FastViT. I think it would be nice to have it here,

• Repo: https://github.com/apple/ml-fastvit
• Paper: https://arxiv.org/abs/2303.14189

Fun Fact: FasterViT from Nvidia came before FastViT from Apple. I think it would be nice to compare them for inference speed.

[leondgarse]

Ok, added in TODO list.

[leondgarse]

It's out, keras_cv_attention_models/fastvit, but still missing the reparameter functions.