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/Client.js

@@ -478,6 +478,17 @@ class Client extends EventEmitter {
         return ContactFactory.create(this, contact);
     }
 
+    /**
+     * Returns an object with information about the invite code's group
+     * @param {string} inviteCode 
+     * @returns {Promise<object>} Invite information
+     */
+    async getInviteInfo(inviteCode) {
+        return await this.pupPage.evaluate(inviteCode => {
+            return window.Store.Wap.groupInviteInfo(inviteCode);
+        }, inviteCode);
+    }
+
     /**
      * Accepts an invitation to join a group
      * @param {string} inviteCode Invitation code