Initialize MegatronBertModel
I would like to initialize a **MegatronBertModel** instead of **TextClassificationModel**, for a classification task. Basically I need to use MegatronBERT based model and tokenizer. I did not find any corresponding config file, how do I configure the YAML config file to achieve this?

Something like this:
```
config = OmegaConf.load(yaml_config)
config.model.language_model.pretrained_model_name = 'biomegatron345m_biovocab_50k_cased'
trainer = pl.Trainer(**config.trainer)
lmodel = MegatronBertModel(config.model, trainer)
```