Literally RCE as a service with training wheels.

Get to dynamically dispatch a C# function from JSON descripiton.

Even the type string is returned to you in the service exception output.

Once you have code execution its a matter of making the flag accessible
through another endpoint, since the program expects an Image return type,
but GetUser returns a String, so an exception is thrown, preventing
you from getting the output directly in the HTTP response.

We move the flag to wwwroot/js/flag.js. Need the extension, since
otherwise the strict web router will not allow us to download it.