Examples compatible with parsers v2.

[kkeroo]

This PR fixes examples so they work with parsers v2. Almost all models from ZOO do work in examples except multi-head models (Hand landmarker, Objectron, Vehicle attributes, Age-Gender).

Additionally, some small bugs were fixed mainly because we defined too strict checks in messages so some edge cases fail:

• Fix score check: if scores are empty array, we can not check the datatype. Fixed in ced692c.
• Correct mask init: We instantiated mask as np.array instead of SegmentationMask. Fixed in 9c9a90c.
• Sometimes values do not meet criteria (between 0 and 1) so clipping is done in parsers. Maybe we could just clip the values inside the message itself? Fixed in 611f8cc.
• Examples are fixed in 63f879c.

If the model has more than one head, error is raised.

[github-actions]

Test Results

125 tests   125 ✅  1s ⏱️
  1 suites    0 💤
  1 files      0 ❌

Results for commit 40a4d18.

♻️ This comment has been updated with latest results.

[github-actions]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
3729	1248	33%	0%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
depthai_nodes/init.py	100%	🟢
depthai_nodes/ml/messages/classification.py	84%	🟢
depthai_nodes/ml/messages/img_detections.py	74%	🟢
depthai_nodes/ml/parsers/keypoints.py	22%	🟢
depthai_nodes/ml/parsers/mediapipe_palm_detection.py	15%	🟢
depthai_nodes/ml/parsers/scrfd.py	19%	🟢
depthai_nodes/ml/parsers/utils/ppdet.py	10%	🟢
depthai_nodes/ml/parsers/yolo.py	19%	🟢
depthai_nodes/ml/parsers/yunet.py	15%	🟢
TOTAL	40%	🟢

updated for commit: 40a4d18 by action🐍

[jkbmrz]

LGTM