add unknown server and unknown player and impl player embed

src/common/embed-fallback.ts

@@ -0,0 +1,23 @@
+import { Metadata } from "next";
+
+type Fallback = {
+  title: string;
+  description: string;
+};
+
+/**
+ * Generates metadata for a fallback embed.
+ *
+ * @param title the title of the embed
+ * @param description the description of the embed
+ * @returns the metadata for the embed
+ */
+export function embedFallback({ title, description }: Fallback): Metadata {
+  return {
+    title: `${title}`,
+    openGraph: {
+      title: `${title}`,
+      description: description,
+    },
+  };
+}