Find epics by searching iid in GraphQL

When filtering for Epics, I want to be able to search by iid using GraphQL.

Search for iid would be not an exact match (e.g. 'get me epic &123) but a search query based on 'beginning with x (e.g. I've just typed &1, give me all the epics that have iids starting with 1). The current AutocompleteService uses EpicsFinder and the GraphQL resolver could perhaps do similar, if not just hooking up to this functionality directly.

Possibly related to: #30421 (depending on the Issue Board implementation)