Use strong encryption in Android KeyStore

Investigate and provide options to configure the following security features for the Android KeyStore:
- [Use StrongBox when possible](https://developer.android.com/reference/android/security/keystore/KeyGenParameterSpec.Builder#setIsStrongBoxBacked(boolean))
- [Require device unlock for operation](https://developer.android.com/reference/android/security/keystore/KeyGenParameterSpec.Builder#setUnlockedDeviceRequired(boolean))
- [Require user authentication](https://developer.android.com/reference/android/security/keystore/KeyGenParameterSpec.Builder#setUserAuthenticationRequired(boolean))
- [Require user confirmation](https://developer.android.com/reference/android/security/keystore/KeyGenParameterSpec.Builder#setUserConfirmationRequired(boolean))

In App Manager, Android KeyStore is used to encrypt/decrypt the password (the decrypted password is always cleared from memory after each operation) for the BKS KeyStore internally used by Android. Therefore, it plays a very important role if the user has encrypted backups present or use a custom signing key.