feat(policy): add context related domain models

...va/eu/teraflow/policy/context/model/ConfigActionEnum.java

...ain/java/eu/teraflow/policy/context/model/ConfigRule.java

...ain/java/eu/teraflow/policy/context/model/Constraint.java

...ain/java/eu/teraflow/policy/context/model/EndPointId.java

...src/main/java/eu/teraflow/policy/context/model/Event.java

...c/main/java/eu/teraflow/policy/context/model/Service.java

.../java/eu/teraflow/policy/context/model/ServiceConfig.java

...main/java/eu/teraflow/policy/context/model/ServiceId.java

.../java/eu/teraflow/policy/context/model/ServiceStatus.java

...a/eu/teraflow/policy/context/model/ServiceStatusEnum.java

...ava/eu/teraflow/policy/context/model/ServiceTypeEnum.java

...ain/java/eu/teraflow/policy/context/model/TopologyId.java

...erated-sources/grpc/service/MutinyServiceServiceGrpc.java

...policy/target/generated-sources/grpc/service/Service.java

...target/generated-sources/grpc/service/ServiceService.java

...et/generated-sources/grpc/service/ServiceServiceBean.java

.../generated-sources/grpc/service/ServiceServiceClient.java

...et/generated-sources/grpc/service/ServiceServiceGrpc.java