Use span with send

[jacobmerson]

I think we should consider bringing in "span-lite" or a different span implementation (since we can't use c++20). I am already doing this in wdmcpl.

If we bring use a span it gives a slightly more safety with the Send call below because we can check that the buffer size is appropriate to be sending.

redev/redev_comm.h

Line 97 in fa3e8e4

virtual void Send(T* msgs) = 0;