Copy ota binaries and build ota section of manifest

[jesserockz]

This updates the action to also produce the ota binary and ota section of the manifest for ota flashing.

{
  "chipFamily": "ESP32",
  "ota": {
    "path": "test-esp32/test-esp32.ota.bin",
    "md5": "a2c4bdfabdfe1cbf459a9ef5e48b767a"
  },
  "parts": [
    {
      "path": "test-esp32/test-esp32.factory.bin",
      "offset": 0
    }
  ]
}

This is a breaking change because the binary for flashing is now named firmware.factory.bin instead of firmware.bin.

In most cases if using this action and the manifest as is, then it should be fine as the manifest contains the path correctly.