Improved Vite rolldown support

[benmccann]

• experimental.enableNativePlugin causes css key to disappear from Vite manifest vitejs/rolldown-vite#320 this affects CSS inlining which also affects our AMP package

See sveltejs/vite-plugin-svelte#1143 for the remaining issues

[ryanylee]

Not sure where to put, but I'm running into an issue where if I have duplicately named files, it causes overwriting. So I have a Alert.svelte in both $lib/ui and $lib/yuzui and the latter gets overwritten by the former in the final build. Interestingly, it's not just .svelte files. I have a file called ClaimsRouting.svelte and claimsRouting.ts that also overwrite each other.

[dominikg]

@ryanylee in a separate issue with a link to a minimal reproduction. Please make sure to mention rolldown-vite and the exact versions you use.