[C++][Python] Add "hypot" compute kernel #50197

Describe the enhancement requested

Arrow's compute layer has no hypot kernel, so computing a Euclidean norm currently requires the verbose and overflow-unsafe sqrt(add(multiply(x, x), multiply(y, y))) (intermediate squaring can overflow even when the result is representable). Add a binary hypot kernel computing $\sqrt{x^2 + y^2}$ safely with std::hypot, matching numpy.hypot, with float32/float64 support and a pyarrow.compute.hypot binding.

Component(s)

C++, Python