Migrate to use DataStore instead of SharedPreferences

[DenBond7]

https://developer.android.com/topic/libraries/architecture/datastore

Settings
https://medium.com/androiddevelopers/all-about-proto-datastore-1b1af6cd2879
https://android-developers.googleblog.com/2020/09/prefer-storing-data-with-jetpack.html
https://developer.android.com/codelabs/android-proto-datastore#1

[DenBond7]

It looks like DataStore doesn't support Settings yet. So we can not drop using SharedPreferences at this stage. I'm moving it to later.