Created by: dzhwinter

Currently, we have two types of Places: CPUPlace and GPUPlace

These are far from sufficient. We might need a hierarchy of more places:

CPUPlace -- X32Place
            X64Place -- MKLPlace
            ARMPlace -- NeonPlace
GPUPlace -- CUDAPlace
            ROCmPlace

Similarly, we have two device-context class CPUDeviceContext and CUDADeviceContext. We need to add more.