Custom domain redirection

### What problem are you trying to solve?

I'm trying to redirect one of my custom domains to another one, but have no way to do so using Deno's dashboard.

### Describe the solution you'd like

I'd like to have a configuration option for my domain where I can specify whether it should be standalone or redirect the traffic to another domain of the project I'm looking at.

### Describe alternatives you've considered

Nothing yet.

### Documentation, Adoption, Migration Strategy

I'd say very similar to how Vercel handles the use case.