Add complex number support to negative

[kgryte]

This PR

• adds complex number support to negative (and __neg__). No special considerations need to be made for complex numbers, as negative follows the rules of complex number multiplication

  $$\textrm{negative}(z_i) = -1\cdot z_i = (-1+0j)\cdot z_i =(-1+0j)\cdot(a_i + b_ij) = (-1a_i + 0b_i) + (0a_i - 1b_i)j = -a_i - b_ij$$

  where $a_i = \textrm{Re}(z_i)$ and $b_i = \textrm{Im}(z_i)$.

[kgryte]

Thanks, @leofang! Will merge, as the changes are straightforward and align with existing array implementations.