Add logical process model and placement algorithm.

[stephenneuendorffer]

Currently, we consider the location where code runs to be physical locations in specific tiles. We should create a logical model of processes and channels (possibly based on the CIRCT handshake dialect) and add a placement algorithm that will locate these processes on particular cores. This model could be similar to the product Vitis tools.

[AndraBisca]

@stephenneuendorffer I think this is supported in current IRON, although more interesting placement algorithms need to be explored.