Prepare api directory for udc mainline branch

udc-extended-api directory will be used only in udc mainline branch to
hide @FlaggedApi annotated api which is not supported in that branch

Copied api directories from udc mainline branch.

Bug: 299411828
Test: TH
Change-Id: I86023b1fb3e5f9b4b787a564303e6d2e60f74467
diff --git a/framework-t/udc-extended-api/removed.txt b/framework-t/udc-extended-api/removed.txt
new file mode 100644
index 0000000..1ba87d8
--- /dev/null
+++ b/framework-t/udc-extended-api/removed.txt
@@ -0,0 +1,9 @@
+// Signature format: 2.0
+package android.net {
+
+  public class TrafficStats {
+    method @Deprecated public static void setThreadStatsUidSelf();
+  }
+
+}
+