[DOC]: Group cuda.cooperative docs

[gevtushenko]

Is this a duplicate?

• I confirmed there appear to be no duplicate issues for this bug and that I agree to the Code of Conduct

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

New

Describe the incorrect/future/missing documentation

As of #1565 CUB docs are grouped by device, block, and warp scopes. On the other hand, cuda.cooperative still has a flat structure 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