Support for larger surfaces in /attributes

Radix accepts requests of maxium size of 100MB.
We send requests as json.

Surfaces are usually large on their own, but we increase request size even more by making them strings.
That means that not only we can't support surfaces > 100MB (which is reality), but we can't support surfaces > 22MB (roughly 100MB after json transformation), or we can't support surfaces > 11MB for attributes/surface/between endpoint as we send two surfaces.

We need to check if we will have to split the request into several or/and send data in binary format instead.