Robolectric shadows: grant access to @hide Wifi APIs

Robolectric can continue to use @hide APIs from
Mainline modules.

Bug: 138801922
Test: m Robolectric_shadows_framework
Change-Id: I331a61d337ec5fe021dfb3e4c9b7246267051517
diff --git a/wifi/Android.bp b/wifi/Android.bp
index 8155922..1d171c7 100644
--- a/wifi/Android.bp
+++ b/wifi/Android.bp
@@ -48,6 +48,7 @@
     "//frameworks/opt/net/wifi/tests/wifitests:__subpackages__",
 
     "//frameworks/opt/net/wifi/libs/WifiTrackerLib/tests",
+    "//external/robolectric-shadows:__subpackages__",
 ]
 
 java_library {