Import and synchronise resources from GOKb

Enable searching/browsing of eresources described within Folio and in external knowledgebases/systems
Where resources are discovered through external systems, allow sufficient information about those eresources to be stored in Folio to make it possible to use those resources as part of agreements (#582) and to track those resources as they change (#585)

If the user identifies a resources which can be added to an agreement (within Folio or by searching an external system from within Folio), should be possible to add that resource to an existing agreement, or use the resource as the basis for creating a new agreement (without having to separately create the new agreement first)