Abbility to set home assistant url when using external ports in the addon

[lieven121]

I was looking for a way to have fusion Fullscreen and would like the ability to navigate. both are not supported by ingress

so next up was using an external port, but this is http which isn't the best
Next up i tried putting it behind my reverse proxy to add a ssl cert
Here I ran into the issue that the proxied version not on port 8099 seems to think my home assistant setup is on the same url
therefor I would like a way to manually define where my home assistant is located like how you can do it with the docker
by setting HASS_URL: http://192.168.1.241:8123
this would preferably be in the addon config screen

I would also like to take this opportunity to say excellent job already, fusion looks good and i would like to see where it goes