Avoid using nb::Result as a return type

[SergioGasquez]

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Pull Request Details 📖

Description

This PR modifies spi/uart/timer to remove some nb::Results and embedded-hal-nb stuff.

• read_byte/write_byte are now blocking for uart and spi.
  • I guess those would be removed in Remove the single byte read/write inherent functions #2808 (i noticed it too late i guess)
• In uart, read_bytes/write_bytes return how many bytes they read/wrote.
  • They will be reworked at Make Uart::read_bytes blocking #2935

Testing

Describe how you tested your changes.

Closes #2729
Closes #2730

[bugadani]

If we're not removing the nb package, should we at least gate it behind unstable?

[SergioGasquez]

If we're not removing the nb package, should we at least gate it behind unstable?

I just removed embedded-hal-nb, the only non-stable driver that was using it was usb_serial_jtag, if anyone has any concerns and prefer to have the traits for it behind the unstable just let me know

[SergioGasquez]

I guess it would be good to resolve #2935 before merging this PR.

[bugadani]

I guess it would be good to resolve #2935 before merging this PR.

No need, I don't mind rebasing that, and you came here first :)

[MabezDev]

Thank you!