Add buildPermissionRequestIntent to PackageManager

Add the buildPermissionRequestIntent API to PackageManager. This allows
an app to request an Intent which, when passed to
startActivityForResult, will prompt the user to approve permissions
for an app.

Currently, the API is @hide.  It will be unhidden in a future change.

Change-Id: I4ec677002afa799a6eb5c2657c28452c91012436