Copy iar/backend assets

Duplicate https://gitlab.developers.cam.ac.uk/uis/devops/iar/backend/tree/master/assets functionality to this repos iar\, api\ and ui\ as appropriate.

added to epic &1 (closed)

added workflowIn Progress label

changed the description

mentioned in merge request !1 (merged)

added workflowReview Required label and removed workflowIn Progress label

closed via merge request !1 (merged)

mentioned in commit d54eada8

added workflowDone label and removed workflowReview Required label