[keyserver] Create an endpoint that allows disabling links
At this point calling the endpoint results in link being deleted. In the future we can consider having a list of disabled links.
Depends on D7885
Test Plan: Tested in combination with the rest of the stack. Confirming disabling a link results in link being deleted.
Reviewers: bartek, kamil, inka
Reviewed By: kamil
Subscribers: ashoat, atul
Differential Revision: https://phab.comm.dev/D7906