PairingFeature

Discovery and pairing of a composable node as a feature (work-placement §WPK-3, §WPI-11).

In the namespace nodekit. Declared in src/libs/libopalnet/opalnet/features/PairingFeature.hpp.

Detailed description

Holds `DiscoveryClient`, its service, and the level `NodeActive-Discovery` that starts it. Needs `identity` and `comms`: discovery announces who this node is, at the address comms binds, and adds what it finds to the address book.

- **Access**: the facility `discoveryClient`, and `trustPeerAt`, the trust that interactive pairing grants, for a peer that the app knows by its key (a join, a hub that a standalone app pairs with). - **Lifecycle**: the discovery service is on the feature's own level, which the app turns on and off (`NodeCommsCoordinator` in a node). It is on no level of the kit. - **Proof**: testNodeKit.

Discovery took a `Node` until §WPI-11. It takes a `DiscoveryHost` now, which this feature fills from the identity and comms features.