perf(@angular-devkit/build-angular): disable ahead of time prerendering in vite dev-server

When using the devserver, instead of prerendering every page for every incremental change, we now perform a server rendering on the page during request time. This ensures that incremental build times are faster when prerending is enabled as we avoid rendering of pages that are never viewed.

Author: alan-agius4

Diff for: packages/angular_devkit/build_angular/src/builders/dev-server/vite-server.ts

@@ -60,6 +60,14 @@ export async function* serveWithVite(
     } as json.JsonObject & BrowserBuilderOptions,
     builderName,
   )) as json.JsonObject & BrowserBuilderOptions;
+
+  if (browserOptions.prerender) {
+    // Disable prerendering if enabled and force SSR.
+    // This is so instead of prerendering all the routes for every change, the page is "prerendered" when it is requested.
+    browserOptions.ssr = true;
+    browserOptions.prerender = false;
+  }
+
   // Set all packages as external to support Vite's prebundle caching
   browserOptions.externalPackages = serverOptions.cacheOptions.enabled;