fix consumed samples calculation + PTune Model bugs
This PR will load the initial consumed samples from the checkpoint file names. The consumed samples will be calculated based on the relative training steps and global batch size.
The T5 doesn't seem to calculate the consumed samples correctly if it supports pipeline parallel. 
```python
    def compute_consumed_samples(self, global_relative_step=0):
        app_state = AppState()
        consumed_samples = (
            self.init_consumed_samples
            + global_relative_step
            * app_state.data_parallel_size
            * self._cfg.micro_batch_size
            * self.trainer.accumulate_grad_batches
        )
        return int(consumed_samples)
```
Need to confirm we will replace `self.trainer.accumulate_grad_batches` with `get_num_microbatches()`