ng serve with traditional backend

### Which @angular/* package(s) are relevant/related to the feature request?

compiler-cli

### Description

I would like to serve the index.html using a traditional backend, and use ng serve to get HMR for the angular app.

The issue with a proxy for the backend API calls is that development and production behave differently. Also, you cant have additional logic on the backend before serving the index.html (for example cookie auth)

### Proposed solution

Have a flag on `ng serve` that the websocket should go directly to the angular server. and would be nice if we can have a single script instead of having to add it all manually.

In vite all you need to do is add the following to your server's HTML template.
```

```
https://vitejs.dev/guide/backend-integration.html

### Alternatives considered

I tried adding the full path to the angular scripts, but the `/ng-cli-ws` calls goes to the backend server.

```

Angular

```

`--public-host=localhost:4200` fixes the /ng-cli-ws call, but lazy loading and the .hot-update.json still goes the backend server.

changing the base href to `https://localhost:4200/` fixes above, but breaks the routing links

also, you need to enable ssl if your backend is ssl, as it will go to wss instead of ws, i think this should rather be based on options.ssl see https://github.com/angular/angular-cli/issues/24373#issue-1475322626.

Start by tracing ng serve handling for /ng-cli-ws, lazy-loaded assets, hot-update files, and the options.ssl behavior, then review the existing public-host flow. Done means a supported way to serve Angular’s development assets and websocket through a traditional backend without breaking backend routing or protocol selection.

Written by the indexing model from the issue text.