feat: Implement get step connection API endpoint

packages/backend/src/controllers/api/v1/steps/get-connection.js

@@ -0,0 +1,11 @@
+import { renderObject } from '../../../../helpers/renderer.js';
+
+export default async (request, response) => {
+  const step = await request.currentUser.authorizedSteps
+    .findById(request.params.stepId)
+    .throwIfNotFound();
+
+  const connection = await step.$relatedQuery('connection').throwIfNotFound();
+
+  renderObject(response, connection);
+};