Ability to set port for browser refresh websocket connection when using dotnet watch

### Is your feature request related to a problem? Please describe.
I am trying to use docker when working with dotnet. Currently when I use dotnet watch a websocket connection is created for browser refresh, but the port is randomly assigned. Because of this I can't set the port in my dockerfile and thus can't use auto refresh in browser.
### Describe the solution you'd like
A way to set the ports for browser refresh. Perhaps in the launch settings as an optional setting. And still assign a random port if no preference is provided.