ENH: sinpi, cospi, asinpi, acospi, etc.: trigonometric functions in units of half turns

Proposed new feature or change:

Alongside the trigonometric functions in units of radians (sin, cos, asin, acos, etc.), C23 and Python 3.16 now have trigonometric functions in units of half turns (sinpi, cospi, asinpi, acospi) which are intended to have reduced or no roundoff error for multiples of pi/4.

Is Numpy the correct place to propose adding these as ufuncs, or should one start at https://github.com/data-apis/array-api?