feat: implement UI for logging out (#638)

* feat: implement UI for logging out

* feat: use old style dialogs for logout confirmation

* feat: implement manage sessions

* feat: implement session logout success dialog

* feat: use snjs alert for revoking sessions confirmation

* fix: make OtherSessionsLogout easier to read

app/assets/javascripts/preferences/panes/account/index.ts

@@ -1,3 +1,4 @@
 export { SubscriptionWrapper } from './subscription/SubscriptionWrapper';
 export { Sync } from './Sync';
 export { Credentials } from './Credentials';
+export { LogOutWrapper } from './LogOutView';