feature #4: create procedure for citizen

resources/functions/citizen/find_citizen_by_id.sql

@@ -0,0 +1,12 @@
+create or replace procedure find_citizen_by_id(in id uuid, inout resource json) language plpgsql as
+$$
+declare
+    _id alias for id;
+begin
+    select to_json(z) into resource
+    from citizen as z
+    where z.id = _id;
+end;
+$$;
+
+-- drop procedure if exists find_citizen_by_id(uuid, inout json);