add searchMessages method (#586)

* add searchMessages method

* fix typing

* fix typing

* remove unused statement

Co-authored-by: Pedro S. Lopez <pslamoros@hotmail.com>

index.d.ts

@@ -99,6 +99,9 @@ declare namespace WAWebJS {
         /** Send a message to a specific chatId */
         sendMessage(chatId: string, content: MessageContent, options?: MessageSendOptions): Promise<Message>
 
+        /** Searches for messages */
+        searchMessages(query: string, options?: { chatId?: string, page?: number, limit?: number }): Promise<Message[]>
+
         /** Marks the client as online */
         sendPresenceAvailable(): Promise<void>