Function aggregate_hours_per_sprint 

fn aggregate_hours_per_sprint(
    time_logs: &[TimeLog],
    burndown_type: &BurndownType,
    burndown_options: &BurndownOptions,
) -> AggregatedHours

Aggregates the logged hours per sprint and calculates the required hours. For BurndownType::PerPerson this returns one series per user. For BurndownType::Total this returns a single "Total" series.

The returned AggregatedHours::total_required_hours contains the total required hours, either per person or for all users combined, depending on burndown_type.