Evaluate script: review of command-line arguments

[sfmig]

This PR changes the CLI arguments of the evaluate script to better match the training script.

The most common use would be to run:

evaluate-detector ---trained_model_path <path-to-ckpt>

This will load the trained model and use its config to run the evaluation. Note that it is important that we use the config used in training, to make the same dataset and use the correct test split.

However, if a dataset or config file is specified via CLI, the parameters will be overwritten.

Other additions

• organises config .yaml parameters into sections (feel free to give feedback, not sure what is most intuitive).
• adds evaluate logs to MLFlow,
• adds a small fix to save frames from test set,
• adds an option to save frames in a selected output directory (if none, uses a timestamped directory),
• fixes test for saving frames and adapt to check timestamped directory.

I will do the tests in a separate PR 😬 ---> #199

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 41.80328% with 71 lines in your changes missing coverage. Please review.

Project coverage is 37.11%. Comparing base (5a47ee0) to head (8bb9d9c).

Files	Patch %	Lines
crabs/detection_tracking/evaluate_utils.py	51.16%	42 Missing :warning:
crabs/detection_tracking/evaluate_model.py	0.00%	28 Missing :warning:
crabs/detection_tracking/visualization.py	85.71%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #172 +/- ## ========================================== - Coverage 37.73% 37.11% -0.63% ========================================== Files 20 20 Lines 1349 1412 +63 ========================================== + Hits 509 524 +15 - Misses 840 888 +48 ```

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