Add Unit Tests for detection_reassembly Module

[RyanDoesMath]

This pull request adds unit tests for the detection_reassembly module. The tests cover the following functionalities:

• intersection_over_union function:
  • Typical inputs with expected IoU calculation.
  • Inputs with no overlap between detections.
  • Inputs with totally overlapping detections.
• non_maximum_suppression function:
  • Typical case with overlapping detections and expected filtering based on confidence score.
  • Empty list of detections as input.

These tests ensure the correctness of the core functionalities in detection_reassembly.