Add support for complex number addition

[kgryte]

This PR

• adds support for complex number addition. Complex number addition is well-defined, where (a + bj) + (c + dj) = (a+c) + (c+d)j.
• Specifies that the special cases described for real-valued floating-point operands apply to the component operations separately. Meaning, operations involving real-valued components (i.e., a, b, c, d) must abide by real-valued floating-point special cases.
• updates the input and output array data types to be any numeric data type, not just real-valued data types.

[rgommers]

This LGTM, thanks @kgryte