STM32H723 support (#21352)

keyboards/handwired/onekey/nucleo_h723zg/info.json

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+{
+    "keyboard_name": "Onekey Nucleo H723ZG",
+    "processor": "STM32H723",
+    "bootloader": "stm32-dfu",
+    "matrix_pins": {
+        "cols": ["A9"],
+        "rows": ["A10"]
+    },
+    "backlight": {
+        "pin": "B8"
+    },
+    "ws2812": {
+        "pin": "A0"
+    },
+    "apa102": {
+        "data_pin": "A0",
+        "clock_pin": "B13"
+    }
+}

keyboards/handwired/onekey/nucleo_h723zg/readme.md

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+# ST Microelectronics Nucleo144-H723 onekey
+
+Supported Hardware: <https://www.st.com/en/evaluation-tools/nucleo-h723zg.html>
+
+To trigger keypress, short together pins *A9* and *A10*.