Support for Mill, scala-cli and other build tools.

[KaranAhlawat]

The Scalajs documentation states that

In this tutorial, we saw how to configure Scala.js with Vite from the ground up using @scala-js/vite-plugin-scalajs. We used sbt as our build tool, but the same effect can be achieved with any other Scala build tool, such as Mill or scala-cli.

But looking at the current implementation (and actual behaviour) it seems like sbt projects are necessary for using this plugin. Therefore, I'd like to request support for Mill and other build tools if possible.