fix: move invite info to client

Since static methods do not have access to `this.client`, it was giving an error when trying to call these functions. The client itself is a better place for them.

close #258

src/structures/GroupChat.js

@@ -136,27 +136,6 @@ class GroupChat extends Chat {
         }, this.id._serialized);
     }
 
-    /**
-     * Returns an object with information about the invite code's group
-     * @param {string} inviteCode 
-     * @returns {Promise<object>} Invite information
-     */
-    static async getInviteInfo(inviteCode) {
-        return await this.client.pupPage.evaluate(inviteCode => {
-            return window.Store.Wap.groupInviteInfo(inviteCode);
-        }, inviteCode);
-    }
-
-    /**
-     * Joins a group with an invite code
-     * @param {string} inviteCode 
-     */
-    static async join(inviteCode) {
-        return await this.client.pupPage.evaluate(inviteCode => {
-            return window.Store.Wap.acceptGroupInvite(inviteCode);
-        }, inviteCode);
-    }
-
     /**
      * Makes the bot leave the group
      */