Add top-level default visibility for Bluetooth module

Bug: 215008564
Test: manual
Tag: #feature
Ignore-AOSP-First: Some changes only present in internal
Change-Id: I0c12526bdf833b41e8d1282b29640fa9481b6a04
diff --git a/Android.bp b/Android.bp
index 2b49380..521a562 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,4 +1,5 @@
 package {
+    default_visibility: [":__subpackages__"],
     default_applicable_licenses: ["system_bt_license"],
 }