Add application instance scaling support

In order to support the "lab timeslots" and enable more efficient of resources by scaling down not used applications the following need to be implemented:

• two additional REST endpoints for triggering the application instance scaling action (either scaling down or up)
• additional application instance state ("scaled down")
• K8s API interaction to run the deployment scaling to appropriate number of replicas

It is assumed that the "scaling schedule" will not be implemented as part of the platform itself but rather by a third party component. The scaling endpoints could be also triggered from the Portal. In this case a new action should be added to the application instance actions menu.