Split `jth_hess_residual` in coord and structure

[tmigot]

NLPModels.jl/src/nls/api.jl

Line 326 in bfd4cea

function jth_hess_residual(nls::AbstractNLSModel{T, S}, x::AbstractVector, j::Int) where {T, S}

The same way we did for jth_hess https://github.com/JuliaSmoothOptimizers/NLPModels.jl/blob/main/src/nlp/api.jl