title: String replacements in index.html in vite
body: <p>I am trying to inject some strings into the index.html of a Vite app (using vue3 template). In a vue-cli project for example we would have</p>
  <p><code>&lt;link rel=&quot;icon&quot; href=&quot;&lt;%= BASE_URL %&gt;favicon.ico&quot;&gt;</code></p>
  <p>What is the Vite way to do that? (I know that BASE_URL is just '/' in this case. I am asking for the general solution) I would be fine with a solution that covers environment variables only, but it would be great to know an even more general solution that can use JS code as in</p>
  <p><code>&lt;title&gt;&lt;%= htmlWebpackPlugin.options.title %&gt;&lt;/title&gt;</code></p>
  <p>And I would really appreciate a solution that doesn't require installing an npm package</p>