Stop suggesting a tutorial completion in every city for a user

[misaugstad]

Brief description of problem/feature

In #3712 we added unified login, so one account now works to log in to each city. When you had to make a new account in each city, we had know way of knowing if someone had completed the tutorial in another city, so they just had to complete the tutorial in every new city where they made an account (of course they could always click the "skip" button). No need for that anymore! Let's show them the tutorial only once!

Potential solution(s)

It might make sense for this to be added as an additional column to the sidewalk_user table? I think that we are just checking for a completed tutorial mission in the mission table right now, but that table is city-specific. When a tutorial is completed, we can just update this new flag in the sidewalk_user table.

It might also be a good idea to just create a new table in the new sidewalk_login schema that holds metadata about a user that is shared between all cities. Maybe we call it global_stats or something? Then there is more info from #3719 that we'd likely want to add to it over time.