rpi-imager json format creation support

[guysoft]

Hey,
So I want to have rpi-imager able to take in CustomPiOS images with as little hassle as possible.
I am adding the tools so nightly builds would let you also have a sniplet per-image build, and then to join them all together

An example format of what should be at the end is here that works with rpi-imager to date:

{
  "os_list": [
    {
      "name": "OctoPi-Klipper (stable)",
      "description": "OctoPi 0.18.0 with latest Klipper",
      "url": "https://github.com/guysoft/OctoPi-Klipper-CustoPiZer/releases/download/0.18.0.klipper.20220109154656/octopi-0.18.0-klipper-20220109154656.zip",
      "icon": "https://github.com/guysoft/OctoPi-Klipper/raw/main/media/rpi-imager-OctoPi-Klipper.png",
      "release_date": "2022-01-09",
      "extract_size": 4609540096,
      "extract_sha256": "0a4ae0ec45a913f251d3fb821c70940d3dcccaf90f6f8db3fe62eae9eee1d138",
      "image_download_size": 1202728211,
      "image_download_sha256": "a10303100e6965a07a65be058790ee49859923493f541da209d8c0656f28b0db"
    }
  ]
}

[guysoft]

So far I think this is implemented and can be closed. If anyone is missing something please voice up here.

wiki entry here:
https://github.com/guysoft/CustomPiOS/wiki/Creating-a-snipplet-to-add-to-rpi-imager

[guysoft]

Closing