Add delete workgroup query & repo

src/main/resources/sql/functions/workgroup/delete_workgroup.sql

@@ -0,0 +1,9 @@
+create or replace function delete_workgroup(_id uuid) returns void
+    language plpgsql as
+$$
+begin
+    update workgroup set deleted_at = now()
+    where id = _id;
+end;
+$$;
+