Context component:

- Updated ConfigRuleModel and separated it into DeviceConfigRuleModel, ServiceConfigRuleModel, SliceConfigRuleModel
- Updated ConstraintModel and separated it into ServiceConstraintModel, SliceConstraintModel
- Updated related indexes
- Activated placeholder for device components
- Updated compose_config_rules_data and upsert_config_rules methods
- Updated compose_constraints_data and upsert_constraints
- Correction of method name SelectDevices to SelectDevice in gRPC servicer