Add auto-detection feature to esp-println

[bjoernQ]

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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.
• My changes are in accordance to the esp-rs API guidelines

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Pull Request Details 📖

Description

Fixes #1576

Using the ROM function didn't work for me - buf_uart_no was always 0 for me but in general I think using SOF-interrupt-flag is a better way to do what we need here.

I also added a CHANGELOG.md for esp-println (but no CI checks for that in this PR)

Testing

Running the examples which use esp-println should print to UART or Serial-JTAG without reconfiguration (or re-compilation).

[JurajSadel]

LGTM, thanks!
I left a very nitpick comment (sorry) I noticed while reading the docs. Feel free to ignore it.

[MabezDev]

Thank you! I think checking the SoF interrupt is much nicer than the ROM function (I think the main reason I went with the ROM function in the stub is that eventually we will also have to detect USB OTG too).

Thanks for adding the changelog too. Would you mind adding esp-println to CI too? After that I think this is ready to go :).

[MabezDev]

Thank you!