[SnackBar] Fix NPE on Android 8 & 9

It seems like on Android 8 & 9 framework's View implementation has a bug that under certain scenarios if we set a view's visibility when view.getParent() is null, it can cause NPE crash.

Fixes this by switching the order of addView and setVisibility() call.

Resolves #917

PiperOrigin-RevId: 413978332

Author: drchen

lib/java/com/google/android/material/snackbar/BaseTransientBottomBar.java

@@ -765,10 +765,11 @@ public void run() {
 
       recalculateAndUpdateMargins();
 
+      targetParent.addView(this.view);
+
       // Set view to INVISIBLE so it doesn't flash on the screen before the inset adjustment is
       // handled and the enter animation is started
       view.setVisibility(View.INVISIBLE);
-      targetParent.addView(this.view);
     }
 
     if (ViewCompat.isLaidOut(this.view)) {