Grant Shell ability to clear cached app data.

It already has CLEAR_APP_USER_DATA to clear everything inside app
storage, and clearing cached data is a subset of that.

Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.StorageHostTest
Bug: 36731175
Change-Id: Iefc5be6c80e2562a95424fd6fe413bdb018201a9
diff --git a/packages/Shell/AndroidManifest.xml b/packages/Shell/AndroidManifest.xml
index 0c4c699..e6d9a9a 100644
--- a/packages/Shell/AndroidManifest.xml
+++ b/packages/Shell/AndroidManifest.xml
@@ -71,6 +71,7 @@
     <uses-permission android:name="android.permission.INSTALL_PACKAGES" />
     <uses-permission android:name="android.permission.MOVE_PACKAGE" />
     <uses-permission android:name="android.permission.CLEAR_APP_USER_DATA" />
+    <uses-permission android:name="android.permission.CLEAR_APP_CACHE" />
     <uses-permission android:name="android.permission.DELETE_CACHE_FILES" />
     <uses-permission android:name="android.permission.DELETE_PACKAGES" />
     <uses-permission android:name="android.permission.ACCESS_SURFACE_FLINGER" />