[FEATURE REQUEST] numpy.copyto

[sfe-SparkFro]

Describe the solution you'd like

Add numpy.copyto

Additional context

Follow up from #726

[v923z]

I think copyto would suffer from the same problems that were discussed in #726: if either the source or the destination are fragmented or do not advance in the same direction, you still have to iterate, you can't copy large chunks of memory.