Update core tools to emit warning if user is running .NET8 inproc app but without `FUNCTIONS_INPROC_NET8_ENABLED`

### Description

Today we require that local.settings.json has `"FUNCTIONS_INPROC_NET8_ENABLED": "1"` for a .NET8 inproc app. A lot of users get confused why the .NET 8 host doesn't launch when they are running an inproc .NET 8 app, so emitting a log/warning would be nice to let them know if they intend on running the .NET 8 host they should set the variable. 