[PMS] Display check-in status for each day of the event

[taesungh]

Following from #341, to indicate who has checked into the event, we can have three columns, one for each day, based on the check-in entries provided by the API. To offload the work from the API, the actual computation of whether or not a participant has checked in on a given day can happen on the client. To avoid a full data refetch, we can Mutate Based on Current Data in the useParticipants hook where the /admin/checkin/{uid} endpoint returns the update data for the current participant.

• Make checkin endpoint return updated check-in entries for the current participant
• Implement the mutation in useParticipant to update the data for only the current participant
• Add three new columns to the participants table showing an icon indicating if a participant has checked in for that day