Add constants for ConnectivityManager.BLOCKED_REASON_*. am: f78a096d9c am: 554d518a34 am: f18f3b733c

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/1676246

Change-Id: I656295d9a24dad25c180f6cf5293e5d97b6cc4cf