Warn about pass conflicts - new pass during an existing passes time

When a new pass is about to be added, add a verification step that checks to see if the time overlaps an existing pass. This way, we don’t end up with passes being cancelled, or field trip passes being added to absent students. There should be a pop-up that says “This pass overlaps with existing passes. Students affected: [include checkboxes, and show photos, names, and current pass]. Uncheck students to exclude from new pass. Continue. Cancel.”