Move some model objects from opennms-webapp to opennms-web-api

This is a subtask from NMS-12941, also the first step of NMS-12941. We want to separate this into a subtask so that we can test this and make sure this didn't break existing stuff before we add new things. 

Move these model objects from opennms-webapp  to opennms-web-api so that we can access them from Rest API as well.
Collection<LldpLinkNode> lldpLinks = enlinkdfactory.getLldpLinks(nodeId);
Collection<BridgeLinkNode> bridgelinks = enlinkdfactory.getBridgeLinks(nodeId);
Collection<CdpLinkNode> cdpLinks = enlinkdfactory.getCdpLinks(nodeId);
Collection<OspfLinkNode> ospfLinks = enlinkdfactory.getOspfLinks(nodeId);
Collection<IsisLinkNode> isisLinks = enlinkdfactory.getIsisLinks(nodeId);
LldpElementNode lldpelem = enlinkdfactory.getLldpElement(nodeId);
CdpElementNode cdpelem = enlinkdfactory.getCdpElement(nodeId);
OspfElementNode ospfelem = enlinkdfactory.getOspfElement(nodeId);
IsisElementNode isiselem = enlinkdfactory.getIsisElement(nodeId);