chore: 🤖 add set-hosts mock endpoint

addons/api/addon/models/host-set.js

@@ -16,14 +16,28 @@ export default class HostSetModel extends GeneratedHostSetModel {
   /**
    * Saves the `host_ids` array on the host set via the `set-hosts` method.
    * See serializer and adapter for more information.
+   * @param {object} options
+   * @param {object} options.adapterOptions
+   * @param {string} options.adapterOptions.hostCatalogID
    * @return {Promise}
    */
-  saveHostIDs() {
-    return this.save({
+  saveHostIDs(options={ adapterOptions: {} }) {
+    const defaultOptions = {
       adapterOptions: {
         method: 'set-hosts',
         serializeHostIDs: true
       }
+    };
+    // There is no "deep merge" in ES.
+    // All of this nonsense is here to ensure we get
+    // a decent merge of `adapterOptions`.
+    return this.save({
+      ...defaultOptions,
+      ...options,
+      adapterOptions: {
+        ...defaultOptions.adapterOptions,
+        ...options.adapterOptions
+      }
     });
   }