Enhancement: Ability to assign administrators as conversation assignees (#2142)

* Enhancement: Ability to assign administrators as conversation assignee

Co-authored-by: Nithin David Thomas <webofnithin@gmail.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/javascript/dashboard/api/inboxes.js

@@ -1,9 +1,14 @@
+/* global axios */
 import ApiClient from './ApiClient';
 
 class Inboxes extends ApiClient {
   constructor() {
     super('inboxes', { accountScoped: true });
   }
+
+  getAssignableAgents(inboxId) {
+    return axios.get(`${this.url}/${inboxId}/assignable_agents`);
+  }
 }
 
 export default new Inboxes();