Add ULP.uart_init method for lp_core

[ameeuw]

Description:

Related issue (if applicable): Builds on #22567 to enable uart communication w/ lp_core

This PR adds a initialisation method for the UART interface of the lp_core of the esp32c6.
The method's signature is

BE_FUNC_CTYPE_DECLARE(be_ULP_uart_init, "", "@iii[i]");

With the arguments being:

• vm
• RX-pin
• TX-pin
• Speed
• optional: Mode (as done in serial)

The method can be used as follows:

import ULP
ULP.uart_init(4,5,9600,serial.SERIAL_8N1)

Open points on implementation:

• RTS- and CTS-pin are left with their default assignment. Should these be exposed in the interface as well? Can they be set to -1 to not use them?

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.8
• The code change is tested and works with Tasmota core ESP32 V.3.1.1.250203
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[Staars]

At first glance I thought we could pack this into ˋgpio_initˋ, but this would probably be quite cumbersome, thus I am fine with this new method.

Can you please refactor it to return an error code instead of ˋvoidˋ and remove all Addlogs. I did not look too deep into it, but maybe we can use -2 and -3 for the wrong pins and the ESP_ERR for the rest.

You use a mixture for C function declaration, that is not in line with most of the rest of this driver and not consistent in itself. Just look at the code for gpio_init in this driver. Your code can be written a bit shorter.

I did not check for the actual functionality. Did you create a working example?

[s-hadinger]

Any news? The PR is still marked as "work in progress"