feat: Implement rest API endpoint to delete flow

packages/backend/src/controllers/api/v1/flows/delete-flow.js

@@ -0,0 +1,10 @@
+export default async (request, response) => {
+  const flow = await request.currentUser.authorizedFlows
+    .clone()
+    .findById(request.params.flowId)
+    .throwIfNotFound();
+
+  await flow.delete();
+
+  response.status(204).end();
+};