Modularize <memory>

[miscco]

This modularizes <memory>.

It either drop deprecated or obsolete content or exposes it through the internal header cuda/std/__memory

Notably this also enables internal use of std::unique_ptr. However, it is currently a bit questionable whether this is the right design as it depends on operator::new.

Before exposing the whole header, we should make some decisions on whether we really want to expose it in this form or whether we want to go with some cuda specific extensions.

[griwes]

There's also compressed_pair.h in __mdspan, please unify if possible.

[miscco]

There is and I want to burn that part with fire. But today is not that day