New index.html format - entrypoint

[BlueCutOfficial]

Context

Lately, we have been working on the inversion of control for the Vite build, we replaced script assets like vendor.js with virtual content Vite can request to Embroider.

Until now, we have never changed the index.html file of the initial Ember app to handle virtualization: in stage 2, the compat-app-builder generates the index.html of the rewritten-app and inserts the virtual entry points. This rewritten file is the one consumed by Vite.

Now that we have virtualized all the entry points, we are ready for the next step that will get us closer to the new blueprint: we are going to write the virtual entry points directly in the index.html of the initial Ember app so Vite will be able to consume it directly, without intermediate change.

This PR handles entrypoint.

[mansona]

looks great! 🎉