Add ngrok shared URL ingress support

[bobzilladev]

Adding an extension for ngrok shared URL's, as an analog to stable-diffusion-webui's ngrok support, using the ngrok-py SDK library. From the README:

Running

To enable ngrok install the requirements and then add --extension ngrok to the command line options, for instance:

pip install -r extensions/ngrok/requirements.txt
python server.py --extension ngrok

In the output you should then see something like this:

INFO:Loading the extension "ngrok"...
INFO:Session created
INFO:Created tunnel "9d9d0944dc75ff9d3aae653e5eb29fe9" with url "https://d83706cf7be7.ngrok.app"
INFO:Tunnel "9d9d0944dc75ff9d3aae653e5eb29fe9" TCP forwarding to "localhost:7860"
INFO:Ingress established at https://d83706cf7be7.ngrok.app

You can now access the webui via the url shown, in this case https://d83706cf7be7.ngrok.app. It is recommended to add some authentication to the ingress, see below.