Add a method in vold to unmount app data and obb dir for testing

This new method will be used in new sm command.
Tests can use this so data and obb dirs are unmounted, and won't
be killed when volume is unmounted.

Bug: 148049767
Test: New sm command able to unmount app's data and obb dirs
Change-Id: Ifbc661ca510e996abd4b7ce1fb195aaa7afc37ad
diff --git a/binder/android/os/IVold.aidl b/binder/android/os/IVold.aidl
index de381d3..19ce9ba 100644
--- a/binder/android/os/IVold.aidl
+++ b/binder/android/os/IVold.aidl
@@ -54,6 +54,7 @@
 
     void remountUid(int uid, int remountMode);
     void remountAppStorageDirs(int uid, int pid, in @utf8InCpp String[] packageNames);
+    void unmountAppStorageDirs(int uid, int pid, in @utf8InCpp String[] packageNames);
 
     void setupAppDir(@utf8InCpp String path, int appUid);
     void fixupAppDir(@utf8InCpp String path, int appUid);