Support CompressedSensingIPM.jl (`FFTKKTSystem`, `GondzioKKTSystem`)

[klamike]

https://github.com/exanauts/CompressedSensingIPM.jl/blob/50fb9c4a4e517a9946d5838fd7d3e3a6ec07d2ce/src/fft_kkt.jl#L91

https://github.com/exanauts/CompressedSensingIPM.jl/blob/50fb9c4a4e517a9946d5838fd7d3e3a6ec07d2ce/src/gondzio_kkt.jl#L99