Support astro & other common FE file extensions (#489)

Closes #462

e2e-tests/astro.spec.ts

@@ -0,0 +1,10 @@
+import { test } from "./helpers/test_helper";
+
+test("astro", async ({ po }) => {
+  await po.setUp({ autoApprove: true });
+  await po.importApp("astro");
+
+  await po.sendPrompt("[dump] hi");
+
+  await po.snapshotServerDump("all-messages");
+});