Missing support for STM32H723VGT6 board (including custom json attempt)

[maarten1C96]

While PlatformIO currently supports the WeAct STM32F411CEU6 (aka 'black pill'), the WeAct STM32H723VGT6 is not being supported yet. The first comes with a 100 MHz CPU, but since the second comes with a 550 MHz CPU my curiosity recently got drawn to the latter. The F411 is working works pretty well in PlatformIO, but would it not be good to support the H723 as well?

_(Although not being experienced in the following, I tried to learn from the STM32duino-, STM32CubeIDE- and Zephyr–, and the blackpill_f411ce.json, genericSTM32F411CC.json and weact_mini_h743vitx.json files. The result is the following, but yet not successful.)_

{
  "build": {
    "arduino": {
      "variant_h": "variant_generic.h"
    },
    "core": "stm32",
    "cpu": "cortex-m7",
    "extra_flags": "-Dstm32h7xx -Dstm32h723xx",
    "f_cpu": "550000000L",
    "framework_extra_flags": {
      "arduino": "-DCUSTOM_PERIPHERAL_PINS"
    },
    "mcu": "stm32h723zgt6",
    "product_line": "STM32H723xx",
    "variant": "STM32H7xx/H723V(E-G)(H-T)_H730VB(H-T)_H733VG(H-T)",
    "zephyr": {
      "variant": "stm32h723xx"
    }
  },
  "debug": {
    "jlink_device": "STM32H723VG",
    "openocd_target": "stm32f7x",
    "svd_path": "STM32F723.svd"
  },
  "frameworks": [
    "arduino",
    "cmsis",
    "stm32cube",
    "libopencm3",
    "zephyr"
  ],
  "name": "WeAct Studio STM32H723VGT6",
  "upload": {
    "maximum_ram_size": 577536,
    "maximum_size": 1048576,
    "protocol": "stlink",
    "protocols": [
      "jlink",
      "cmsis-dap",
      "stlink",
      "blackmagic",
      "serial",
      "dfu"
    ]
  },
  "url": "https://github.com/WeActStudio/WeActStudio.MiniSTM32H723",
  "vendor": "WeAct Studio"
}