feat: Create modal to merge two contacts (#2457)

app/javascript/dashboard/api/accountActions.js

@@ -0,0 +1,18 @@
+/* global axios */
+
+import ApiClient from './ApiClient';
+
+class AccountActions extends ApiClient {
+  constructor() {
+    super('actions', { accountScoped: true });
+  }
+
+  merge(parentId, childId) {
+    return axios.post(`${this.url}/contact_merge`, {
+      base_contact_id: parentId,
+      mergee_contact_id: childId,
+    });
+  }
+}
+
+export default new AccountActions();