Trainer.model.push_to_hub() should allow private repository flag
### Feature request

Trainer.model.push_to_hub() should allow a push to a private repository, as opposed to just pushing to a public and having to private it after.

### Motivation

I get frustrated having to private my repositories instead of being able to upload models by default to a private repo programmatically.

### Your contribution

I’m not sure I have the bandwidth at the moment or have the infrastructure know how to contribute this option, but if this is of interest to many people and you guys could use the help I can work on a PR.
Hi @arikanev, thanks for raising this issue. 

In `TrainingArguments` you can set [hub_private_repo to `True`](https://huggingface.co/docs/transformers/v4.31.0/en/main_classes/trainer#transformers.TrainingArguments.hub_private_repo) to control this. <|||||>Thanks for the heads up! Time saver :) <|||||>Please note, I tried using this in TrainingArguments and it did not work! I set hub_private_repo to True.<|||||>Hi @arikanev, OK thanks for reporting.. 

So that we can help, could you provide some more details: 
* A minimal code snippet to reproduce the issue 
* Information about the running environment: run `transformers-cli env` in the terminal and copy-paste the output 
* More information about the expected and observed behaviour: when you say it didn't work, what specifically? Did it fail with an error, not create a repo, create a public repo etc? 