feat: support `.test` domains for local dev

Description

Many local development tools expose projects on .test domains instead of localhost. One example is Lerd, which serves projects as my-app.test.

It would be nice if Vite had first-class support for .test domains during development, making local development feel closer to a real production environment.

Suggested solution

Add a simple option in the Vite config to automatically expose the dev server on projectName.test (or another configurable .test domain), instead of only using localhost.

Example:

export default defineConfig({
  server: {
    localDomain: {
      enabled: true,
      domain: "my-app.test",
    },
  },
})

Which would expose the project at:

https://my-app.test

Additional context

Lerd is a good example of this workflow on Linux for PHP/Laravel projects, and it's a very nice developer experience when working with Vite.