handle sending group SMS

- in Context.getMessages, split the sender number by spaces " " to get each contact.
- apply update in the android-smsmms lib - do not pass threadId in Transaction.sendNewMessage

app/src/main/kotlin/com/simplemobiletools/smsmessenger/services/HeadlessSmsSendService.kt

@@ -30,7 +30,7 @@ class HeadlessSmsSendService : Service() {
             transaction.setExplicitBroadcastForSentSms(smsSentIntent)
             transaction.setExplicitBroadcastForDeliveredSms(deliveredIntent)
 
-            transaction.sendNewMessage(message, getThreadId(number))
+            transaction.sendNewMessage(message)
         } catch (ignored: Exception) {
         }