GitLab

* [legacy] move trainer to legacy

* [doc] update docs related to trainer

* [test] ignore legacy test

* Update colotensor_concept.md

* Update configure_parallelization.md

* Update define_your_config.md

* Update engine_trainer.md

* Update initialize_features.md

* Update model_checkpoint.md

* Update colotensor_concept.md

* Update configure_parallelization.md

* Update define_your_config.md

* Update engine_trainer.md

* Update initialize_features.md

* Update model_checkpoint.md