Fix visualize_keypoints3d_projected method

[ghost]

The visualize_project_keypoints3d does not exist anymore. This PR updates the mview_mperson_topdown_estimator.py estimator method to use the new function, visualize_keypoints3d_projected.

I also had to add the folder creation function for the output videos, as the first time that it runs, the folder doesn't exist and the script crashes there.

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