Fixed #14037 - record current time on accessory checkin

[snipe]

Since accessory checkin (or chicken, as autocorrect would have it) allows you to specify a date, we were treating that datetime as a date field, without providing any hour information. This now takes the current time and appends it correctly.

[shortcut-integration]

This pull request has been linked to Shortcut Story #24356: Accessory check-in not recording the correct time.

[what-the-diff]

PR Summary

• Added Check-in Duration Variable
  This update introduces a new component known as checkin_hours which stores the duration for which a user stays after checking in.
• Updated Check-in Time Calculation
  The checkin_at component, responsible for managing the exact check-in times, is also updated. It now takes into account the newly added checkin_hours value during its operations. This means, when you provide the duration of your stay, the system seamlessly includes it in calculating your check-in time. This will provide more accurate information about user's stay duration and can help in managing resources more effectively.