Fix to ODIDDataSource for calculating datarate for negative streams (cvp...

Fix to ODIDDataSource for calculating datarate for negative streams (cvp2ri-433)
    
When doing the byterate calculation (for adjusting chunk size in live streaming), the total duration was taken from the last entry of the content file regardless of direction. For negative-rate content this duration needs to be taken from the first entry.

Fixed the ODIDDataSource to pass the direction into the duration extraction functions and updated the functions to factor in duration.
Will this cause problems if the index file doesn't exist? When making this same call below, you check if the index file exists first.