feat: add support for svelte-4 prereleases (#661)

* feat: add svelte 4 to peer dependency range and update test snapshots

* chore: update snapshot to match svelte-4 compiler output

* fix(types): only use CompileOptions.format with svelte3

* fix: update test snapshot to match latest version-4 output

* fix: separate snapshots between svelte-3 and svelte-4 for compiler output

* feat(inspector): enable svelte-4 peer

* fix: use ts-ignore instead of expect-error to avoid unused directive fail

* chore: fix indentation

Author: dominikg

.changeset/angry-spiders-attack.md

@@ -0,0 +1,8 @@
+---
+'@sveltejs/vite-plugin-svelte-inspector': minor
+'@sveltejs/vite-plugin-svelte': minor
+---
+
+Add support for svelte-4 prereleases
+
+Note: We are going to remove `^4.0.0-next` from the peerDependency range in another minor release after svelte `4.0.0` final has been released.