[FEA]: Implement P2642: Padded layouts

[miscco]

Is this a duplicate?

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

Area

libcu++

Is your feature request related to a problem? Please describe.

The padded layouts are essential for interop with a lot of fundamental C-libraries like BLAS

Given that the paper has been merged into the C++ standard we should implement them.

• Implement std::layout_left_padded
• Implement std::layout_right_padded

Describe the solution you'd like

Implement std::layout_right_padded and std::layout_left_padded as described in the latest C++standard

Describe alternatives you've considered

There shall only be one standard

Additional context

No response

[bdice]

Is this a duplicate of #2808?

We would like this feature for rapidsai/raft#2836 / rapidsai/raft#1616.

[fbusato]

yes, it is a duplicate

[bdice]

I'm going to use my triage powers to close this in favor of #2808, since that is part of a larger epic.