Interface that defines the function of resource demands depending on provided external constraints.
In order to support primitive balancing, the function it two-phased:
During the first phase the function computes demands independently of external constraints.
Resource plan defines the set of activities that require the host resources.
All activities in the system are treated as a temporary activities, clients are responsible for declaring their
initiation/closure via respective API of the IHostResourceManagementHandle to allow the resource management
facility to balance resources.