chore: Move to Typescript (#2783)

This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.

closes #1282

shared/utils/slugify.ts

@@ -0,0 +1,10 @@
+import slugify from "slugify"; // Slugify, escape, and remove periods from headings so that they are
+// compatible with url hashes AND dom selectors
+
+export default function safeSlugify(text: string) {
+  return `h-${escape(
+    slugify(text, {
+      lower: true,
+    }).replace(".", "-")
+  )}`;
+}