Add imports to networking test mapping

Ensure that appropriate networking tests are triggered when submitting
changes in the frameworks/base directories.

Change-Id: Ibf8b567fa7721299120b0a6c6836dd770d92a9fc
Test: treehugger runs TEST_MAPPING tests

tests/net/TEST_MAPPING

@@ -8,5 +8,10 @@
     {
       "name": "FrameworksNetDeflakeTest"
     }
+  ],
+  "imports": [
+    {
+      "path": "cts/tests/tests/net"
+    }
   ]
 }