On dashboard startup, check if ports are in use before starting Kestrel

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

If the dashboard is started while a previous instance is running the user sees an unfriendly error message that the port is already in use. This will cause the dashboard startup to fail.

### Describe the solution you'd like

Two things:
1. Poll if ports are in use. If they are then wait a short time (5 seconds?) and try again. Makes dashboard more resilient
2. Throw a friendly error message to the user.

### Additional context

_No response_