Add `cuda.core.utils.get_aligned_dtype`

[leofang]

Many CUDA Python projects require the ability to declare a custom alignment for a give dtype. While NumPy builtin/structure dtypes work in most cases, this is one of the few issues that it cannot fulfill today. @seberg has figured out a prototype to address this issue (https://github.com/numpy/numpy/issues/28318#issuecomment-2678883667), and the plan is for cuda.core to provide this infrastructure, let other teams start using it, gather feedbacks, and eventually upstream this back to NumPy.