Add Support for LuxCore.Internal.get_empty_state in KolmogorovArnold.jl

[chooron]

Hello, thank you very much for your work in implementing KAN. I am currently looking to integrate the KANs you developed into ModelingToolkit.jl, which requires the representation of equations. The approach I am following is based on ModelingToolkitNeuralNets.jl, where the core idea is to convert the LuxCore.stateless_apply method into equations.

However, after trying this approach, I found that the current version of KolmogorovArnold.jl does not support LuxCore.Internal.get_empty_state, which prevents me from using LuxCore.stateless_apply to convert it into equations. To make this work, and in alignment with the model algorithms, I would like to request that the repository add an interface for LuxCore.Internal.get_empty_state, as follows:

LuxCore.Internal.get_empty_state(l::KDense) = (;grid = collect(LinRange(l.grid_lims..., l.grid_len)))

I am not sure if this method is correct, but I hope you can add support for this method in your future work. Thank you!

[vpuri3]

can you create a pull request?