[Validate] add warning for unspecified arguments, and change default values

[sasha-scale]

Fixes some problems with 3D evaluation metrics and adds unit test coverage on the numerical correctness of metric functions.

Specific issues found:

• enforcing label matches not properly taken into account by 3D metrics.
• default IoU threshold of 0.0 causing some hidden unexpected behavior
• incorrect weight/denominator for iou matches. Should divided by number of valid IoU matches, rather than # of predictions or # of annotations