feat(pcf): created SM association is stored in hashmap with uid

src/api-server/impl/SMPoliciesCollectionApiImpl.cpp

src/api-server/pcf-api-server.h

src/pcf_app/CMakeLists.txt

src/pcf_app/pcf_sm_policy_control.cpp

src/pcf_app/pcf_sm_policy_control.hpp

src/pcf_app/sm_policy/individual_sm_association.cpp

src/pcf_app/sm_policy/individual_sm_association.hpp