Replaced Utilities.isNycOrAbove() with version code check.

- Instead of using reflection to check if N is present, we now use
  Build.VERSION.SDK_INT >= Build.VERSION_CODES.N.
- Other places that used reflection to use N APIs have also been
  cleaned up.

Bug: 22942492
Change-Id: Ia7b981cae375e800bcc8f0c54aec48e0c8c076da

src/com/android/launcher3/util/PackageManagerHelper.java

@@ -62,7 +62,7 @@ public class PackageManagerHelper {
         // The value of FLAG_SUSPENDED was reused by a hidden constant
         // ApplicationInfo.FLAG_PRIVILEGED prior to N, so only check for suspended flag on N
         // or later.
-        if (Utilities.isNycOrAbove()) {
+        if (Utilities.ATLEAST_N) {
             return (info.flags & FLAG_SUSPENDED) != 0;
         } else {
             return false;