Storage: migrate from react-native-encrypted-storage to react-native-keychain

[kaloudis]

react-native-encrypted-storage is now archived, whereas react-native-keychain is actively maintained. Both leverage the system keychain storage so they should be equally secure in concept.

We would want to add a migration in SettingsStore for users to have their data seamlessly transferred. We would want to take Settings, Contacts, and Note objects all into account and test on both Android and iOS.

https://github.com/oblador/react-native-keychain

[kaloudis]

Another option: react-native-mmkv

#2372

[kaloudis]

User reported storage issues:

#1463
#1966