improve support for auto mapping / loading components

[thescientist13]

Currently the integration assumes that for a component tag name like this

<x-greeting></x-greeting>

It will assume that there is a corresponding file in a components directory, e.g.

src/
  components
    greeting.js

Ideally, we should be able to use some sort of Astro / Vite internals to find the source of these components, since they would need to be in the head anyway, e.g.

<script src="../components/greeting.js"></script>