Support search for sibling identifier in Agreements -> E-resources search

Purpose:

Currently the text search in Agreements -> E-resources supports a search for identifier which finds all resources linked to the identifier. However it does not find resources based on identifiers on sibling title instances. 

Because the search only finds electronic title instances and packages, the outcome for the user is that it is not currently possible to find resources (books, journals) by identifiers for print instances (e.g. print ISSN / ISBN)

The requirement is that a user should be able to successfully find a electronic title instance in the search by searching for an identifier attached to one of it's sibling (print) title instances.

User story statement(s):

As a ERM librarian
I want find a electronic title instance when searching for an identifier attached to a sibling print instance
so that I can find titles by identifier no matter which instance the identifier is attached to

Scenarios:

1. Scenario:
   • Given a title instance A with subType=electronic, with a sibling title instance B (i.e. title instance for the same work) with an identifier C
   • When I search for identifier C
   • Then title instance A is included in the results

Dev task breakdown

As this is written I don't believe it's possible.

This likely needs a new method on the controller, which specifically will look for any titleInstances with that identifier OR any titleInstances which have property 'work' equal to same as one which matches from identifier, then look only for the electronic ones.

• Create new method on controller
• Write query (HQL) which does the above
• Create new endpoint
• Frontend work to utilise that endpoint. Likely will need to be a different "kind" of search, maybe a dropdown beneath Search Bar