Do not export private AIDL files of the media module

The current directory contains public and private AIDL types in the same place.
This CL separates into two directories and makes the directory having the
public types should be exported.

Bug: 148660295
Test: build
Change-Id: Ib2632afa00f7fa7f992690e68684464928cd3c61

Android.bp

@@ -339,9 +339,7 @@ java_defaults {
             "sax/java",
             "telecomm/java",
 
-            // TODO(b/148660295): remove this
-            "apex/media/framework/java",
-
+            "apex/media/aidl/stable",
             // TODO(b/147699819): remove this
             "telephony/java",
         ],