Add API to get current firewall chain status

This commit adds ConnectivityManager#getFirewallChainEnabled to read the
current firewall chain status

Bug: 208371987
Test: m
Change-Id: I1eadb69f953af5d031cd8dabde3e1f098cf0f4df

service/src/com/android/server/ConnectivityService.java

@@ -11383,6 +11383,13 @@ public class ConnectivityService extends IConnectivityManager.Stub
         }
     }
 
+    @Override
+    public boolean getFirewallChainEnabled(final int chain) {
+        enforceNetworkStackOrSettingsPermission();
+
+        return mBpfNetMaps.getChainEnabled(chain);
+    }
+
     @Override
     public void replaceFirewallChain(final int chain, final int[] uids) {
         enforceNetworkStackOrSettingsPermission();