Update (most of) the distributed tree internals to use given execution space
Created by: dalg24
Haven't dealt with Details::DistributedSearchTreeImpl::sendAcrossNetwork()
nor Details::Distributor
but I need to focus on other stuff
Note that I suspect we could avoid initializing a few views. We should get into the habit to comment when the view constructor will initialize and we intended for it. There are a few places where it we set all values but the last one in a parallel for and then perform an exclusive scan. This is easy to overlook and then we are back in UB land.