esp32/boards/SOLDERED_NULA_MINI: Add new board definition.

Add support for the upcoming Soldered NULA Mini ESP32C6 board by Soldered
Electronics.

Signed-off-by: Josip Šimun Kuči <josipsimunkuci@gmail.com>

ports/esp32/boards/SOLDERED_NULA_MINI/board.json

@@ -0,0 +1,23 @@
+{
+    "deploy": [
+        "../deploy.md"
+    ],
+    "deploy_options": {
+        "flash_offset": "0"
+    },
+    "docs": "",
+    "features": [
+        "BLE",
+        "WiFi",
+        "USB-C",
+        "JST-PH"
+    ],
+    "images": [
+        "soldered-nula-mini-esp32c6.jpg"
+    ],
+    "mcu": "esp32c6",
+    "product": "NULA Mini",
+    "thumbnail": "",
+    "url": "https://soldered.com/product/nula-mini-esp32-c6/",
+    "vendor": "Soldered Electronics"
+}

ports/esp32/boards/SOLDERED_NULA_MINI/mpconfigboard.cmake

@@ -0,0 +1,8 @@
+set(IDF_TARGET esp32c6)
+
+set(SDKCONFIG_DEFAULTS
+    boards/sdkconfig.base
+    boards/sdkconfig.riscv
+    boards/sdkconfig.c6
+    boards/sdkconfig.ble
+)

ports/esp32/boards/SOLDERED_NULA_MINI/mpconfigboard.h

@@ -0,0 +1,10 @@
+// This configuration is for a generic ESP32C6 board with 4MiB (or more) of flash.
+
+#define MICROPY_HW_BOARD_NAME               "Soldered NULA Mini"
+#define MICROPY_HW_MCU_NAME                 "ESP32C6"
+
+// Enable UART REPL for modules that have an external USB-UART and don't use native USB.
+#define MICROPY_HW_ENABLE_UART_REPL         (1)
+
+#define MICROPY_HW_I2C0_SCL      (7)
+#define MICROPY_HW_I2C0_SDA      (6)

ports/esp32/boards/SOLDERED_NULA_MINI/pins.csv

@@ -0,0 +1,7 @@
+IO2,GPIO2
+IO3,GPIO3
+IO4,GPIO4
+IO5,GPIO5
+IO18,GPIO18
+IO19,GPIO19
+USER_BUTTON,GPIO9