Based on the Android API Council guideline, we should avoid using the
Enum structure to define the constant definition.
go/android-api-guidelines#avoid-enum
Bug: 197595292
Test: make SettingsRoboTests
Change-Id: I4b22f0abde7f4ce2c3a0b076db786e619783d93e
This change is to reduce ambiguity as we're adding the option to style the preference like a checkbox as well.
Bug: 190180868
Test: SelectorWithWidgetPreferenceTest, RunSettingsLibRoboTests
Change-Id: Ie414347bf67ed394ef495604890c5851fc42dbc7