Generate a placeholder image based on a provider, width, and height.
Use this tool to generate a placeholder image for testing or development purposes.
Args:
provider: The provider to use for the image, must be either `placehold` or `lorem-picsum`.
width: The width of the image, must be a positive integer between 1 and 10000.
height: The height of the image, must be a positive integer between 1 and 10000.