Protect against lack of WRITE_SYSTEM_SETTINGS AppOp

Guard the following entry points with checks against the AppOp

1) Launch of SoundSettingsFragment
Fallback: Send to system sound settings instead

2) onResume of SoundSettingsFragment (this can happen if the AppOp
is toggled by the user in the background)
Fallback: Return to main Dialer settings instead

3) Toggling of various perferences (this can happen in monkey tests)
Fallback: Show toast, ignore settings chance

Bug: 22660372

Change-Id: Ief5d74166d35a9718ea664f378f6930e777f2923