feat-preferences: data backup export and import (#646)

* feat: data backups initial implementation

* feat: improve data backups design in preferences

* feat: split import backup in multiple segments

* feat(preferences): move import backup spinner next to import button

* fix(data-backups): padding between radio btn and buttons

app/assets/javascripts/preferences/panes/security-segments/index.ts

@@ -1,3 +1,4 @@
 export * from './Encryption';
 export * from './PasscodeLock';
 export * from './Protections';
+export * from './DataBackups';