fixed schedule for streams spanning multiple days

[karjo24]

Motivation and Context

See #1484.

Description

If a stream spans over multiple days, the corresponding calendar item between the start and end day will not have an inner element containing a start and end time. However, the function that injects the location into the calendar item will do so by appending the new location item to the time item. In the case of streams with duration >2d, the time item does not exist. This PR fixes this by manually injecting a custom time item when it doesn't exist yet.

Steps for Testing

Prerequisites:

• 1 Admin

1. Add a scheduled stream to the database. It must end at least 2 calendar days after the start time.
2. Log in
3. Navigate to a Admin Schedule
4. See that no error is logged to the console, the left and right day/week navigation keys still work and the calendar item contains 12:00 - 12:00 as the time and a valid location.