Let tests enumerate all transports/capabilities.

This gives them a way to collect all included values without
resorting to manual probing of each newly added value.

Cherry-pick of ag/4052941 with minor conflicts in the imports.

Bug: 16207332
Test: atest com.android.cts.net.HostsideVpnTests
Change-Id: Ia764b3412bf834890612378e0c3846913f4e0a06
Merged-In: Ie5cd22cfa2b6a60510fd1e31d7ebcd8f6cc890a0
Merged-In: If07e77c92046807235229a4f67ee087bdd7bccf1

core/java/android/net/NetworkCapabilities.java

@@ -18,6 +18,7 @@ package android.net;
 
 import android.annotation.IntDef;
 import android.annotation.SystemApi;
+import android.annotation.TestApi;
 import android.net.ConnectivityManager.NetworkCallback;
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -435,6 +436,7 @@ public final class NetworkCapabilities implements Parcelable {
      * @return an array of capability values for this instance.
      * @hide
      */
+    @TestApi
     public @NetCapability int[] getCapabilities() {
         return BitUtils.unpackBits(mNetworkCapabilities);
     }
@@ -699,6 +701,7 @@ public final class NetworkCapabilities implements Parcelable {
      * @return an array of transport type values for this instance.
      * @hide
      */
+    @TestApi
     public @Transport int[] getTransportTypes() {
         return BitUtils.unpackBits(mTransportTypes);
     }