19027: sys/fmt: optimize scn_u32_dec scn_u32_hex r=benpicco a=kfessel

### Contribution description

Improves the compilation result for `scn_u32_dec` `scn_u32_hex` especially on `cortex-m` reducing either stack usage and or code size.

This makes use of unsigned int overflow (slightly less better without doing that `hexn`).

See godbolt (original versions got an `o` attached, modified versions got `k`s) all functions are  marked `_S_` defined to `static`

by assigning the global at end the compiled function can be changed (`deco deck  hexo hexk hexkk hexn`)

this PR is `hexkk` and `deck` 

### Testing procedure

run unit-test/test-fmt

```
<RIOT>/tests/unittests$ make tests-fmt
<RIOT>/tests/unittests$ make term
```

### Issues/PRs references

[godbolt](https://godbolt.org/z/MzT1zh4q1)

19269: cpu/gd32v/periph_i2c: interrupt based driver r=benpicco a=gschorcht

### Contribution description

This PR provides an interrupt-driven version of the I2C low-level driver.

The existing I2C low-level driver for GDVF103 uses a busy-waiting approach where the status register is continuously polled while waiting for a certain status when sending or receiving. The MCU is thus occupied the whole time during a send or receive operation.

The driver provided with this PR uses an interrupt-driven approach. This is, while waiting for a certain status when sending or receiving, the calling thread is suspended and woken up by interrupts.

Since the I2C controller allows to receive up to two bytes before the application has to react, receiving a single byte, two bytes or more than two bytes needs a different handling for correct receiption. This requires a tricky implementation which distinguish a number of different case. There the driver requires 860 byte more ROM and 8 byte more RAM.

### Testing procedure

The driver should work with any I2C sensor/actuator. It was tested with
- `tests/driver_bmp180`
   <details>
  
   ```
    main(): This is RIOT! (Version: 2023.04-devel-355-g940c7-cpu/gd32v/periph_i2c_interrupt_driven)
    BMP180 test application
    
    +------------Initializing------------+
    Initialization successful
    
    +------------Calibration------------+
    AC1: 8448
    AC2: -1208
    AC3: -14907
    AC4: 33310
    AC5: 24774
    AC6: 19213
    B1: 6515
    B2: 49
    MB: -32768
    MC: -11786
    MD: 2958
    
    +--------Starting Measurements--------+
    Temperature [°C]: 22.0
    Pressure [hPa]: 1006.49
    Pressure at see level [hPa]: 1025.55
    Altitude [m]: 157
    
    +-------------------------------------+
    Temperature [°C]: 22.0
    Pressure [hPa]: 1006.56
    Pressure at see level [hPa]: 1025.58
    Altitude [m]: 157
    
    +-------------------------------------+
   ```
   
   </details>
- `tests/driver_ccs811`
   <details>
  
   ```
    main(): This is RIOT! (Version: 2023.04-devel-355-g940c7-cpu/gd32v/periph_i2c_interrupt_driven)
    CCS811 test application
    
    +------------Initializing------------+
    
    +--------Starting Measurements--------+
    TVOC [ppb]: 0
    eCO2 [ppm]: 0
    +-------------------------------------+
    TVOC [ppb]: 0
    eCO2 [ppm]: 0
    +-------------------------------------+
    TVOC [ppb]: 0
    eCO2 [ppm]: 0
    +-------------------------------------+
    TVOC [ppb]: 0
    eCO2 [ppm]: 400
    +-------------------------------------+
    TVOC [ppb]: 0
    eCO2 [ppm]: 400
    +-------------------------------------+
    TVOC [ppb]: 0
    eCO2 [ppm]: 400
    +-------------------------------------+
    TVOC [ppb]: 7
    eCO2 [ppm]: 446
    +-------------------------------------+
    TVOC [ppb]: 7
    eCO2 [ppm]: 446
    +-------------------------------------+
    TVOC [ppb]: 7
    eCO2 [ppm]: 446
    +-------------------------------------+
    TVOC [ppb]: 7
    eCO2 [ppm]: 446
    +-------------------------------------+
    ```
   
   </details>
- `tests/driver_sht3x`
   <details>
  
    ```
    main(): This is RIOT! (Version: 2023.04-devel-355-g940c7-cpu/gd32v/periph_i2c_interrupt_driven)
    SHT3X test application
    
    +------------Initializing------------+
    Initialization successful
    
    
    +--------Starting Measurements--------+
    Temperature [°C]: 21.46
    Relative Humidity [%]: 54.50
    +-------------------------------------+
    Temperature [°C]: 21.47
    Relative Humidity [%]: 54.53
    +-------------------------------------+
    Temperature [°C]: 21.46
    Relative Humidity [%]: 54.48
    +-------------------------------------+
    Temperature [°C]: 21.46
    Relative Humidity [%]: 54.47
    +-------------------------------------+
    ```
   
   </details>
- `tests/driver_l3gxxxx`
   <details>
  
    ```
    main(): This is RIOT! (Version: 2023.04-devel-375-g75547-cpu/gd32v/periph_i2c_interrupt_driven)
    L3GXXXX gyroscope driver test application
    
    Initializing L3GXXXX sensor
    [OK]
    
    gyro [dps] x:    +0, y:    -1, z:    -2
    gyro [dps] x:    +0, y:    +0, z:    +0
    gyro [dps] x:    +0, y:    +0, z:    +0
    gyro [dps] x:    +0, y:    +0, z:    +0
    gyro [dps] x:    +0, y:    +0, z:    +0
    gyro [dps] x:    +0, y:    +0, z:    +0
    gyro [dps] x:    -1, y:    +0, z:    +4
    gyro [dps] x:    +0, y:    +0, z:   -21
    gyro [dps] x:    +0, y:    +0, z:    +6
    gyro [dps] x:   -43, y:    +0, z:   -13
    gyro [dps] x:   -21, y:    -2, z:    +0
    gyro [dps] x:    +0, y:    +1, z:    +3
    gyro [dps] x:   +25, y:    +0, z:    +0
    ```
   
   </details>
- `tests/driver_hd44780` with `pcf8574a` I2C interface

### Issues/PRs references



19284: boards: support for the LILYGO TTGO T8 ESP32-S2 board r=benpicco a=gschorcht

### Contribution description

This PR provides the support for the LILYGO TTGO T8 ESP32-S2 board which has a OLED display (not yet supported) and a SD-Card slot on board.

The board is equipped with a USB-C connector that connects either to a USB-to-UART bridge or to the USB-OTG/JTAG interface of the ESP32-S2 via some DIP switches.

The PR includes a very small fix of printf format string in `tests/malloc`. I can split it off.

### Testing procedure

t.b.d.

### Issues/PRs references


19286: cpu/esp_common: use generic WIFI_SSID/WIFI_PASS defines r=benpicco a=benpicco



Co-authored-by: Karl Fessel <[email protected]>
Co-authored-by: Gunar Schorcht <[email protected]>
Co-authored-by: Benjamin Valentin <[email protected]>