add all2all interaction in Rydberg atom chain system

[hongyehu]

The default of Rydberg chain system is changed to

function RydbergChainSystem(;
    N::Int=3, # number of atoms
    C::Float64=862690*2π,  
    distance::Float64=8.7, # μm
    cutoff_order::Int=1, # 1 is nearest neighbor, 2 is next-nearest neighbor, etc.
    local_detune::Bool=false,
    all2all::Bool=true,
)

And when all2all is true, all interactions between atoms are active.