Function safe_arch::cast_from_m256i_to_m256

#[must_use]pub fn cast_from_m256i_to_m256(a: m256i) -> m256

This is supported with target feature avx only.

Bit-preserving cast from m256i to m256.

let a = m256i::from([1.0_f32.to_bits(); 8]);
let b = cast_from_m256i_to_m256(a).to_array();
assert_eq!(b, [1.0; 8]);