Now that we can enforce 2FA we also should notify users that have
enabled 2FA but do not yet have backup codes generated.
This adds a repair step that inserts a background job to do this.
Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>
Generate a notification to generate backup codes if you enable an other
2FA provider but backup codes are not yet generated.
* Add event listner
* Insert background job
* Background job tests and emits notification every 2 weeks
* If the backup codes are generated the next run will remove the job
Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>