[common] (pipeline) Add validation support

...common/pipeline/classification/classification_pipeline.py

...polystar/common/pipeline/classification/classifier_abc.py

...n/polystar/common/pipeline/classification/random_model.py

common/polystar/common/utils/markdown.py

...h/robots_at_robots/armor_color/armor_color_benchmarker.py

...robots/research/robots_at_robots/armor_color/benchmark.py

...h/robots_at_robots/armor_digit/armor_digit_benchmarker.py

...robots/research/robots_at_robots/armor_digit/benchmark.py

...-robots/research/robots_at_robots/evaluation/benchmark.py

...t_robots/evaluation/image_pipeline_evaluation_reporter.py

...at-robots/research/robots_at_robots/evaluation/trainer.py