Add members settings (#2788)

* Update GroupChat.js

* Update index.d.ts

* style: clarify method doc

* refactor: add additional check

* fix: provide valid error name

---------

Co-authored-by: alechkos <93551621+alechkos@users.noreply.github.com>

src/structures/GroupChat.js

@@ -281,6 +281,27 @@ class GroupChat extends Chat {
         return true;
     }
     
+    /**
+     * Updates the group setting to allow only admins to add members to the group.
+     * @param {boolean} [adminsOnly=true] Enable or disable this option 
+     * @returns {Promise<boolean>} Returns true if the setting was properly updated. This can return false if the user does not have the necessary permissions.
+     */
+    async setAddMembersAdminsOnly(adminsOnly=true) {
+        const success = await this.client.pupPage.evaluate(async (groupId, adminsOnly) => {
+            const chatWid = window.Store.WidFactory.createWid(groupId);
+            try {
+                const response = await window.Store.GroupUtils.setGroupMemberAddMode(chatWid, 'member_add_mode', adminsOnly ? 0 : 1);
+                return response.name === 'SetMemberAddModeResponseSuccess';
+            } catch (err) {
+                if(err.name === 'SmaxParsingFailure') return false;
+                throw err;
+            }
+        }, this.id._serialized, adminsOnly);
+
+        success && (this.groupMetadata.memberAddMode = adminsOnly ? 'admin_add' : 'all_member_add');
+        return success;
+    }
+    
     /**
      * Updates the group settings to only allow admins to send messages.
      * @param {boolean} [adminsOnly=true] Enable or disable this option