do not allow using the app, if it isnt the default SMS handler

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

@@ -0,0 +1,11 @@
+package com.simplemobiletools.smsmessenger.services
+
+import android.app.Service
+import android.content.Intent
+import android.os.IBinder
+
+class HeadlessSmsSendService : Service() {
+    override fun onBind(intent: Intent?): IBinder? {
+        return null
+    }
+}