feat: policy calls service rpc (wip)

proto/policy_action.proto

src/policy/mvnw

...y/src/main/java/eu/teraflow/policy/PolicyServiceImpl.java

src/policy/src/main/java/eu/teraflow/policy/Serializer.java

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

...n/java/eu/teraflow/policy/model/PolicyRuleActionEnum.java

.../main/java/eu/teraflow/policy/service/ServiceGateway.java

...n/java/eu/teraflow/policy/service/ServiceGatewayImpl.java

.../main/java/eu/teraflow/policy/service/ServiceService.java

...n/java/eu/teraflow/policy/service/ServiceServiceImpl.java

src/policy/src/main/resources/application.yml

...licy/src/test/java/eu/teraflow/policy/SerializerTest.java

...get/generated-sources/grpc/context/ContextOuterClass.java

...target/generated-sources/grpc/context/ContextService.java

...et/generated-sources/grpc/context/ContextServiceBean.java

.../generated-sources/grpc/context/ContextServiceClient.java

...et/generated-sources/grpc/context/ContextServiceGrpc.java

...erated-sources/grpc/context/MutinyContextServiceGrpc.java

...nerated-sources/grpc/kpi_sample_types/KpiSampleTypes.java

.../target/generated-sources/grpc/monitoring/Monitoring.java