:sparkles: Validation & Handle Negative Index Wrap

[ajinkya-kulkarni]

1. The function now raises a ValueError if the downsample factor is not greater than 0 - downsample_shape
2. wrap_index includes handling negative indices and indices that exceed the bounds of the array.
3. view_as_blocks includes checking that the block shape is a divisor of the array shape to avoid errors, and removing the unnecessary numpy.ravel() call.

[John-P]

I am curious what your use case is for negative indexing with the wrap_index function, as it is only used when writing files which must be in increasing order.