[mednet.tests] Move tests to single directory

...on/data/histograms/raw_data/histograms_iostar_vessel.json

...ion/data/histograms/raw_data/histograms_jsrt_default.json

...ta/histograms/raw_data/histograms_montgomery_default.json

...ation/data/histograms/raw_data/histograms_refuge_cup.json

...ata/histograms/raw_data/histograms_rimoner3_cup_exp1.json

...data/histograms/raw_data/histograms_shenzhen_default.json

...ntation/data/histograms/raw_data/histograms_stare_ah.json

tests/segmentation/test_chasedb1.py

tests/segmentation/test_cli_segmentation.py

tests/segmentation/test_cxr8.py

tests/segmentation/test_drhagis.py

tests/segmentation/test_drionsdb.py

tests/segmentation/test_drishtigs1.py

tests/segmentation/test_drive.py

tests/segmentation/test_hrf.py

tests/segmentation/test_iostar.py

tests/segmentation/test_jsrt.py

tests/segmentation/test_measures.py

tests/segmentation/test_montgomery.py

tests/segmentation/test_refuge.py