[FEA]: Add RAII-style discard_memory to new vsmem utilities

[elstehle]

Is this a duplicate?

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Area

CUB

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

The new utilities for virtual shared memory also add a static member function that helps to hint to discard any dirty cachelines that are part of the virtual shared memory of that thread block. It's easy to forget adding this to the end of the kernel, like:

...
  agent.Process();
...
  // If applicable, hints to discard modified cache lines for vsmem
  VSmemHelperT::discard_temp_storage(temp_storage);

Describe the solution you'd like

It would be nice to make this call RAII-style, such that we automatically discard_memory, once the helper goes out of scope.

Describe alternatives you've considered

No response

Additional context

No response