Move TtyMode into its own ListPreference class.

This allows the class and behaviors to be reused in
CallFeaturesSetting and PhoneAccountSettingsActivity.

Adjust logic so that for MSIM devices, TTY appers in the
PhoneAccountSettingsFragment instead of CallFeaturesSetting.

Bug: 16844188
Change-Id: Ifcc70d674a59f0195b00155ca346f03677ade8d2
6 files changed