Backend refactor (#120)

* remove spqlios, split cpu_ref and cpu_avx into different crates

* remove spqlios submodule

* update crate naming & add avx tests

poulpy-cpu-avx/benches/vmp.rs

@@ -0,0 +1,11 @@
+// poulpy-backend/benches/vec_znx_add.rs
+use criterion::{Criterion, criterion_group, criterion_main};
+use poulpy_cpu_avx::FFT64Avx;
+use poulpy_hal::bench_suite::vmp::bench_vmp_apply_dft_to_dft;
+
+fn bench_vmp_apply_dft_to_dft_cpu_avx_fft64(c: &mut Criterion) {
+    bench_vmp_apply_dft_to_dft::<FFT64Avx>(c, "FFT64Avx");
+}
+
+criterion_group!(benches_x86, bench_vmp_apply_dft_to_dft_cpu_avx_fft64,);
+criterion_main!(benches_x86);