V3/auto accept

[dunkOnIT]

This replaces #10381 - I needed to make thewca the base repo for the first PR so that the diff on the 2nd PR wouldn't be absurdly long like the last time I branched off an in-review PR.

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Lots to do here, will probably just handle basic pending -> accepted case in this PR.

Implementation Thoughts

• I'm adding an auto_accept method on the registration model. I think this should ultimately be where our auto_accept logic lives, and that is what will get called even if we have multiple entry points for auto_accepting. For example:
  • creation of a RegistrationPayment has an after_create hook that calls registration.auto_accept
  • if we want to do a BulkAutoAccept job, it can just iterate through the pending registrations in order of payment and call auto_accept on each of them

This PR

• Add auto-accept and auto-accept-cutoff settings to competition table
• Make them available in the competition form
• Add tests for auto-accept functionality
• Add tests for auto-accept cutoff
• Hide it behind a feature flag? Or just give organizers a way to turn it off

Next PR

• Give organizers a way to toggle auto-accept on/off
• Give organizers a way to run a bulk auto-accept
• Automatically run bulk auto-accept when auto-accept is toggled on
  • Warn organizers this will happen, and give them an "Are you sure?" dialogue, where saying "No" will

Later PR's

• Auto-accept users onto waiting list when Accepted is full
  • Should they be accepted onto the waiting list if the auto-accept-cutff has been reached?
  • If so, then we should also implement a warning when an organizer tries to approve a user from the pending list while there are users in the waiting list
• Auto-accept users from waiting list if a spot becomes available in the accepted list (ie, if an attendee's status changes away from accepted

Questions:

• Should we default to 0 or NULL if no auto_accept_threshold is set
• Think carefully about naming of db fields

[FinnIckler]

You could have still branched off your PR but squashed your previous commits using rebase (which you can then drop after merge)