refactor: message decoding

1. removes redundant receipt (was exactly the same as delivery receipt without the timestamp)
2. decodeWAMessage now returns a proper message struct
3. each message stanza results in exactly one message decoded

src/Socket/messages-send.ts

@@ -73,7 +73,10 @@ export const makeMessagesSocket = (config: SocketConfig) => {
         }
         return mediaConn
     }
-
+    /**
+     * generic send receipt function 
+     * used for receipts of phone call, read, delivery etc.
+     * */
     const sendReceipt = async(jid: string, participant: string | undefined, messageIds: string[], type: 'read' | 'read-self' | undefined) => {
         const node: BinaryNode = {
             tag: 'receipt',
@@ -107,10 +110,6 @@ export const makeMessagesSocket = (config: SocketConfig) => {
         await sendNode(node)
     }
 
-    const sendDeliveryReceipt = (jid: string, participant: string | undefined, messageIds: string[]) => {
-        return sendReceipt(jid, participant, messageIds, undefined)
-    }
-
     const sendReadReceipt = async(jid: string, participant: string | undefined, messageIds: string[]) => {
         const privacySettings = await fetchPrivacySettings()
         // based on privacy settings, we have to change the read type
@@ -424,7 +423,7 @@ export const makeMessagesSocket = (config: SocketConfig) => {
 		...sock,
         assertSessions,
         relayMessage,
-        sendDeliveryReceipt,
+        sendReceipt,
         sendReadReceipt,
         refreshMediaConn,
 	    waUploadToServer,