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

index.d.ts

@@ -10,6 +10,9 @@ declare namespace WAWebJS {
     /**Accepts an invitation to join a group */
     acceptInvite(inviteCode: string): Promise<void>
 
+    /**Returns an object with information about the invite code's group */
+    getInviteInfo(inviteCode: string): Promise<object>
+
     /** Enables and returns the archive state of the Chat */
     archiveChat(): Promise<boolean>