[FEATURE] Add settings sync

[Myzel394]

Add settings sync using:

• Nostr relays
• iCloud
• Android (Google probably)

[Myzel394]

related to #124 (comment)

[Myzel394]

@Korb you can already export and import the settings, why would you like to be able to sync your settings?

[Korb]

@Myzel394, every user has dozens of applications installed on their smartphone. Their settings generally differ from the original ones. The average user does not export the settings of all installed applications that support export on a weekly basis. The user remembers this only when he loses his smartphone, or breaks it, or drowns it. If cloud synchronization is available, the user only needs to log into his account on the new smartphone so that all applications installed on the old smartphone are installed and their user settings are applied. In the absence of cloud synchronization (at the level of Google or the application infrastructure), the user will have to configure everything from scratch, in each such application. And it’s good if he remembers exactly what settings he had in each such application.

[JFingerle]

I'm using Locus on devices without gapps / Google Services Framework. When implementing this please make sure users without gapps can continue using Locus.
Thank you and and all contributers for this awesome app.