fix (onboarding): popbackstack before navigating to map screen so that you can't go back to onboarding screen

Signed-off-by: sds100 <developer.sds100@gmail.com>

Author: sds100

app/src/main/java/com/mapcode/onboarding/OnboardingScreen.kt

@@ -59,8 +59,8 @@ fun OnboardingScreen(
         modifier = modifier,
         onFinishOnboarding = {
             viewModel.onFinishOnboarding()
-            navigator.navigate(MapScreenDestination.route)
             navigator.popBackStack()
+            navigator.navigate(MapScreenDestination.route)
         },
         layoutType = layoutType
     )