let the dispose method delegate to stop() on Android

Author: navaronbracke

android/src/main/kotlin/dev/steenbakker/mobile_scanner/MobileScanner.kt

@@ -512,7 +512,10 @@ class MobileScanner(
      * Dispose of this scanner instance.
      */
     fun dispose() {
-        scanner?.close()
-        scanner = null
+        if (isStopped()) {
+            return
+        }
+
+        stop() // Defer to the stop method, which disposes all resources anyway.
     }
 }