Replace lookupproxy api

Removing lookupproxy means that some functionality used by the frontend (particularly institutions) is now missing.

added to epic &1 (closed)

mentioned in issue #10 (closed)

mentioned in merge request !4 (merged)

mentioned in issue #11 (closed)

mentioned in merge request !14 (merged)

Completed by last UI component in MR for #22 (closed).

changed milestone to %Sprint 91

added workflowReview Required label

assigned to @rjg21

mentioned in issue #3 (closed)

mentioned in commit 25d5a6f0

closed via merge request !14 (merged)

added workflowDone label and removed workflowReview Required label