Add the content_to_string utility.

utilities/content-to-string.typ

@@ -0,0 +1,15 @@
+// Convert a `Content` type to a string by recursively going through it and
+// collecting any text nodes, discarding everything else.
+// Copied from GitHub:
+// https://github.com/typst/typst/issues/2196#issuecomment-1728135476
+#let content_to_string(content) = {
+  if content.has("text") {
+    content.text
+  } else if content.has("children") {
+    content.children.map(content_to_string).join("")
+  } else if content.has("body") {
+    content_to_string(content.body)
+  } else if content == [ ] {
+    " "
+  }
+}