Support advanced reporting with Linked Epics API

Problem

(from customer) We wish to do some reports internally on dependencies, and therefore need to use the linked epics api to gather data. However, there are a few problems with the available APIs as per https://docs.gitlab.com/ee/api/linked_epics.html as we can't currently fetch only where there are updates; we have to keep checking every item each time which isn't workable at scale. We have ideas but are open to alternative suggesetions

Proposal

• Support querying all links for a given group as at the moment you have to check every single epic separately to see if it has links
• Support filtering and sorting by link_updated_at to allow for incremental queries
• Fields needed:
  • Source issue/epic id
  • Target issue/epic id
  • Link type
  • Link created/updated at