Add feature to export devices as, at least, CSV

[Username1111111111]

Add abbility to export already scanned devices list as CSV, including attached tags, MAC, device name, detection time, amount of detections, (might be locations?). Also add feature to export individualy choosen devices (or even one).

[Semper-Viventem]

There is a database backup functionality in the settings, which allows you to export the whole SQLite database from the app. I'll consider adding also CSV format in the future.