Implement background tasks and more

Fixes SQL queries to determine station status
- Only tournaments reservations for tournaments currently in progress are returned
- Only reservations for reservations currently in progress are returned
Started work on propagating reservation errors from to the management page
- Errors are propagated but not yet displayed in the modal component, needs UI work
- Implemented background tasks to automatically expire reservations
- Expired reservations are set deleted in the db after their end time lapses
- Pubsub messages are sent to mark stations with expired reservations available
- Can add LDAP logic there
- Expiration tasks are created for active reservations on app start up in case of restart/crash
- Fixed bug for deleting reservations if a station somehow ends up with more than one active reservation

otakulan / lanparty-seating