UART: Make the tx_fifo_count and is_tx_idle UART functions public

[MikeGstefan]

Thank you for your contribution!

We appreciate the time and effort you've put into this pull request.
To help us review it efficiently, please ensure you've gone through the following checklist:

Submission Checklist 📝

• I have updated existing examples or added new ones (if applicable).
• I have used cargo xtask fmt-packages command to ensure that all changed code is formatted correctly.
• My changes were added to the CHANGELOG.md in the proper section.
• I have added necessary changes to user code to the Migration Guide.
• My changes are in accordance to the esp-rs API guidelines

Extra:

• I have read the CONTRIBUTING.md guide and followed its instructions.

Pull Request Details 📖

Description

Marked the fn is_tx_idle(&self) and fn tx_fifo_count(&self) as public as my project requires access to these functions.

Testing

Compilation was successful and all examples execute

[Dominaezzz]

The names could use some improving before going public imo

At least remove tx from the names.

[MabezDev]

Marked the fn is_tx_idle(&self) and fn tx_fifo_count(&self) as public as my project requires access to these functions.

Would you mind explaining a bit about your use case and why these need to be exposed?

[MikeGstefan]

Would you mind explaining a bit about your use case and why these need to be exposed?

My board has external drivers with additional inputs that need to be manually controlled. The state of these pins is dependent on the uart buffer state.