[Examples] Replicates the new --log_level feature to all trainer-based pytorch
# What does this PR do?
Fixes #12295 

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [x] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [x] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [x] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/master/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/master/docs#writing-source-documentation).
- [ ] Did you write any new necessary tests?

## Notes:
- The required changes are added for all the trainer-based examples except `run_generation.py` since it seems very different.
- Please let me know if any modification needed.

## Who can review?
@stas00  @sgugger 

Also as mentioned earlier, let's add:
```
    transformers.utils.logging.enable_default_handler()
    transformers.utils.logging.enable_explicit_format()
```
everywhere they are missing - I see there are quite a few places.

Thank you!<|||||>@bhadreshpsavani, we forgot to take care of the template `templates/adding_a_new_example_script/\{\{cookiecutter.directory_name\}\}/run_\{\{cookiecutter.example_shortcut\}\}.py`
if you don't mind adding this change there too in another PR.
 
Thank you!
<|||||>Sure I will add it,
Ya, i totally forgot!