Always provide const values for rust

[crop2000]

This commit removes the -uim flag for rust and provides the const values by default and makes use of these const values in get_num_inputs and get_num_outputs it also simplifies how this functions are generated they are now just a string

To create arrays for compute_arrays() one needs to know the array sizes at compile time. The const definitions provide these.

[crop2000]

@bluenote10 I am quite sure that this will not break anything. but can you have a look.

[crop2000]

I moved the const definition just before the struct definition. I think this pr is ready for merging

[crop2000]

@sletz are you open to merge this?

[sletz]

Thanks.