[DOC]: Group cuda.cooperative docs

### Is this a duplicate?

- [x] I confirmed there appear to be no [duplicate issues](https://github.com/NVIDIA/cccl/issues) for this bug and that I agree to the [Code of Conduct](CODE_OF_CONDUCT.md)

### Is this for new documentation, or an update to existing docs?

New

### Describe the incorrect/future/missing documentation

As of https://github.com/NVIDIA/cccl/pull/1565 CUB docs are [grouped](https://nvidia.github.io/cccl/cub/modules.html) by device, block, and warp scopes. On the other hand, cuda.cooperative still has a [flat structure](https://nvidia.github.io/cccl/cuda_cooperative/) with all the API on one page.

We should partition cuda.cooperative documentation into block and warp pages as well.

### If this is a correction, please provide a link to the incorrect documentation. If this is a new documentation request, please link to where you have looked.

_No response_