[pm/uninstall] check if data still exists on any other users before fully uninstall

Use ceDataInode as an indicator of whether the app data directory still
exists for a given user. This allows preservation of user data if the
user specified DELETE_KEEP_DATA, even after another user attempts to
fully uninstall the app.

FIXES: 296284876
BUG: 288142708
Test: manual with steps in the bug and verify that the user data is
preserved and the package setting remained

Change-Id: Ic936b8a54481aa9d9a2b92f86bd6d2f238895200