"CA cert installed" notification should take PO into account

- PO shows same dialog as DO, as shown in UI mock
- Keep consumer message the same
- Add cancel button
- string change
- remove TYPE_SYSTEM_ALERT due to the bug that the dialog is shown in primary user and bypass work challenge
  (Step: unlock work user -> launch dialog -> lock work user -> unlock personal user -> the dialog is still shown)
- Remove dismissKeyguard, because I believe the dialog should still be protected by the keyguard

Bug: 25772443
Bug: 18224038
Change-Id: I4f2580d1f6d2f88cfeadebcf6e8b0406e5c4b413