This adds a new table UserNotificationSchedules which stores monday-friday start and ends times that each user would like to receive notifications (with a Boolean enabled to remove the use of the schedule). There is then a background job that runs every day and creates do_not_disturb_timings for each user with an enabled notification schedule. The job schedules timings 2 days in advance. The job is designed so that it can be run at any point in time, and it will not create duplicate records.
When a users saves their notification schedule, the schedule processing service will run and schedule do_not_disturb_timings. If the user should be in DND due to their schedule, the user will immediately be put in DND (message bus publishes this state).
The UI for a user's notification schedule is in user -> preferences -> notifications. By default every day is 8am - 5pm when first enabled.
