implement Thread Border Router e2e integration test

This implements a basic border routing test case (ping) and demonstrates a
valid test environment for Thread Border Router test cases.

Later we can add more packet verifications and more test cases.

Bug: 295843010
Test: atest android.net.ThreadBorderRouterTest

Change-Id: Ifb9b6d45539143a227c2bc0ed69b5c3167ef9acd
diff --git a/framework/Android.bp b/framework/Android.bp
index 7ec3971..f3d8689 100644
--- a/framework/Android.bp
+++ b/framework/Android.bp
@@ -190,6 +190,7 @@
         "//packages/modules/Connectivity/Cronet/tests:__subpackages__",
         "//packages/modules/Connectivity/Tethering/tests:__subpackages__",
         "//packages/modules/Connectivity/tests:__subpackages__",
+        "//packages/modules/Connectivity/thread/tests:__subpackages__",
         "//packages/modules/IPsec/tests/iketests",
         "//packages/modules/NetworkStack/tests:__subpackages__",
         "//packages/modules/Wifi/service/tests/wifitests",