Remove duplicate detections between BARD and Yolo .sqlite

[Myfanwy]

BARD and Yolo databases contain overlapping/duplicate detections - these should be identified, and the duplicates removed from the BARD database prior to joining the two.

[mespe]

This gets done automatically using ybt::ybt_db_append() - the script R/combine_bard_yolo.R (761a511) does flag the duplicates to ensure they match with what the function reports.