Back up the smooth display setting

- Convert "Smooth display" and "Force peak refresh rate" to a boolean. If they are a boolean, they can be backed up without being device-specific.
- Back up "Smooth display" and add a validator
- Upgrade the settings in SettingsProvider
- Create a utils class - RefreshRateSettingsUtils

Bug: 211737588
Test: atest DisplayModeDirectorTest
Test: atest ForcePeakRefreshRatePreferenceControllerTest
Test: atest PeakRefreshRatePreferenceControllerTest
Test: atest SettingsBackupTest
Test: atest SettingsProviderTest
Test: atest RefreshRateSettingsUtilsTest
Change-Id: Ib2cb2dd100f06f5452083b7606109a486e795a0e
Merged-In: Ib2cb2dd100f06f5452083b7606109a486e795a0e