feat(wandb): save model as artifact (#8119)

* feat(wandb): log artifacts

* fix: typo

* feat(wandb): ensure name is allowed

* feat(wandb): log artifact

* feat(wandb): saving logic

* style: improve formatting

* fix: unrelated typo

* feat: use a fake trainer

* fix: simplify

* feat(wandb): log model files as artifact

* style: fix style

* docs(wandb): correct description

* feat: unpack model + allow env Truethy values

* feat: TrainerCallback can access tokenizer

* style: fix style

* feat(wandb): log more interesting metadata

* feat: unpack tokenizer

* feat(wandb): metadata with load_best_model_at_end

* feat(wandb): more robust metadata

* style(wandb): fix formatting

src/transformers/trainer.py

@@ -261,7 +261,9 @@ class Trainer:
                 "You should subclass `Trainer` and override the `create_optimizer_and_scheduler` method."
             )
         callbacks = DEFAULT_CALLBACKS if callbacks is None else DEFAULT_CALLBACKS + callbacks
-        self.callback_handler = CallbackHandler(callbacks, self.model, self.optimizer, self.lr_scheduler)
+        self.callback_handler = CallbackHandler(
+            callbacks, self.model, self.tokenizer, self.optimizer, self.lr_scheduler
+        )
         self.add_callback(PrinterCallback if self.args.disable_tqdm else DEFAULT_PROGRESS_CALLBACK)
 
         # Will be set to True by `self._setup_loggers()` on first call to `self.log()`.