Create Checkpoint Check-in

Need to connect Rideboard before this can be implemented
For every CAR n rideboard, have those people on a NEW TAB called "checkin table"
At every checkin, the Driver (or someone in the car) will be able to checkbox the checkin they hit, so Potter/Earlycrew can see where people are at

Start by finding the Rideboard entry point and the structure for adding a new tab, then determine how riders are grouped by car. Done means each car’s riders appear in a Checkin Table, drivers or car members can mark the checkpoints they reach, and Potter/Earlycrew can see the current status.

Written by the indexing model from the issue text.