feat: Pin and unpin Chats (#166)

* Added Pinning
- chat.pin() to pin
- chat.unpin() to unpin

Co-authored-by: Pedro S. Lopez <pedroslopez@me.com>

index.d.ts

@@ -17,7 +17,13 @@ declare namespace WAWebJS {
     getInviteInfo(inviteCode: string): Promise<object>
 
     /** Enables and returns the archive state of the Chat */
-    archiveChat(): Promise<boolean>
+    archiveChat(chatId: string): Promise<boolean>
+
+    /** Pins the Chat and returns its new Pin state */
+    pinChat(chatId: string): Promise<boolean>
+
+    /** Unpins the Chat and returns its new Pin state */
+    unpinChat(chatId: string): Promise<boolean>
 
     /**
      * Create a new group
@@ -679,6 +685,10 @@ declare namespace WAWebJS {
 
     /** Archives this chat */
     archive: () => Promise<void>,
+    /** Pins this chat and returns its new Pin state */
+    pin: () => Promise<boolean>,
+    /** Unpins this chat and returns its new Pin state */
+    unpin: () => Promise<boolean>,
     /** Clears all messages from the chat */
     clearMessages: () => Promise<boolean>,
     /** Stops typing or recording in chat immediately. */