[API] Expose IpSecTunnelInterface#setUnderlyingNetwork

This API is required to perform MOBIKE. This API allows an IPsec
peer to change the underlying network of its established IPsec
tunnel without re-establishing the tunnel.

Bug: 169855650
Test: atest IpSecManagerTunnelTest (new tests added)
Change-Id: Ifc8ad902cbfbe4ad07e715f2fef0faa1bf9d68f3
diff --git a/core/java/android/net/IpSecManager.java b/core/java/android/net/IpSecManager.java
index 55fdafc..98acd98 100644
--- a/core/java/android/net/IpSecManager.java
+++ b/core/java/android/net/IpSecManager.java
@@ -801,7 +801,6 @@
          * @param underlyingNetwork the new {@link Network} that will carry traffic for this tunnel.
          *     This network MUST never be the network exposing this IpSecTunnelInterface, otherwise
          *     this method will throw an {@link IllegalArgumentException}.
-         * @hide
          */
         // TODO: b/169171001 Update the documentation when transform migration is supported.
         // The purpose of making updating network and applying transforms separate is to leave open