feat: Show icon on external links (#3100)

* feat: External links get treatment

* cache decorations

shared/editor/queries/findLinkNodes.ts

@@ -0,0 +1,19 @@
+import { Node } from "prosemirror-model";
+import { findTextNodes, NodeWithPos } from "prosemirror-utils";
+
+export default function findLinkNodes(doc: Node): NodeWithPos[] {
+  const textNodes = findTextNodes(doc);
+  const nodes: NodeWithPos[] = [];
+
+  for (const nodeWithPos of textNodes) {
+    const hasLinkMark = nodeWithPos.node.marks.find(
+      (mark) => mark.type.name === "link"
+    );
+
+    if (hasLinkMark) {
+      nodes.push(nodeWithPos);
+    }
+  }
+
+  return nodes;
+}