Simplify CPL framework to be more suitable for kea-netconf
The CPL framework that was initially designed and developed for D2 and was later used for CA is considered superior to what DHCPv4 and DHCPv6 use. However it has a number of disadvantages that should be mitigated:
- way too many classes needed (agent, classes derived derived from controller, process, DCfgContextBase, DCfgMgrBase)
- lack of common class to store logging information (Daemon from libdhcpsrv is used for this, resulting in the need to include libdhcpsrv library everywhere)