Adding IDR(s) from IterativeSolvers.jl

[mschauer]

Currently IDR(s) from IterativeSolvers.jl is missing iterator support. There is a PR JuliaLinearAlgebra/IterativeSolvers.jl#345 adding that support, so IDR(s) can be added to this package in a next step. I followed the example of GMRES so this should be possible?

[mschauer]

That is merged now, we can continue here.