Platform shouldn't directly link to jars in APEXes

The non-updatable part of the platform shouldn't directly link to the
boot jars in APEXes. Ensure this by

1) setting the visibility property for the boot jars so that they are
not visible to non-APEX modules and
2) setting the apex_available property so that the boot jars are only
built for the corresponding APEXes, but not for others.

Bug: None
Test: m
Change-Id: I6130b64790b9892a60bc0704a5b60a0fffa89f34
diff --git a/service/Android.bp b/service/Android.bp
index 084b45c..5d23aa5 100644
--- a/service/Android.bp
+++ b/service/Android.bp
@@ -155,6 +155,15 @@
     init_rc: ["wifi.rc"],
 
     plugins: ["java_api_finder"],
+
+    visibility: [
+        "//frameworks/opt/net/wifi/service/apex",
+        "//frameworks/opt/net/wifi/tests/wifitests/apex",
+    ],
+    apex_available: [
+        "com.android.wifi",
+        "test_com.android.wifi",
+    ],
 }
 
 // Westworld auto-generated code