Add parameter selection to UI

[najann]

• [x] give users the possibility to change the values for threshold & confidence
• [x] keep default values
• [x] find example images where different values produce different predictions

[najann]

For the sake of simplicity and speed I added 2 dropdown options for threshold & confidence with pre-selected defaults.

[najann]

Parameter_Impact_YOLO.pdf This PDF provides some examples how confidence score & nms threshold impact the number of objects detected