feat: add comments/presi eplus promos for discoveribility (#10294)

excalidraw-app/components/ExcalidrawPlusPromoBanner.tsx

@@ -0,0 +1,22 @@
+export const ExcalidrawPlusPromoBanner = ({
+  isSignedIn,
+}: {
+  isSignedIn: boolean;
+}) => {
+  return (
+    <a
+      href={`${
+        isSignedIn
+          ? import.meta.env.VITE_APP_PLUS_LP
+          : import.meta.env.VITE_APP_PLUS_APP
+      }/plus?utm_source=excalidraw&utm_medium=app&utm_content=${
+        isSignedIn ? "signedInBanner" : "guestBanner"
+      }#excalidraw-redirect`}
+      target="_blank"
+      rel="noopener"
+      className="plus-banner"
+    >
+      Excalidraw+
+    </a>
+  );
+};