Add API Endpoint for inspection schedule

**Is your feature request related to a problem? Please describe.**
There is currently an API endpoint to get the inspection status, but there is no way to get the schedule.

**Describe the solution you'd like**
An API endpoint returning the inspection schedule. It could be in basically the same format as `http://localhost/event/:eventId/inspection_schedule/raw/`, but provided through the API.

**Describe alternatives you've considered**
Currently the only ways to get this information in an officially supported way is to export the schedule as CSV.

**Additional context**
N/A

Start by locating the existing API endpoint for inspection status and the event/:eventId/inspection_schedule/raw/ route mentioned in the issue. Compare their response conventions and determine how the schedule should be exposed through the API. Done means an officially supported endpoint returns the inspection schedule in the agreed format without requiring CSV export.

Written by the indexing model from the issue text.