kafka/metadata_response: Add custom formatter specialization

And remove `operator<<`

Signed-off-by: Oren Leiman <[email protected]>

Author: oleiman

src/v/kafka/protocol/metadata.h

@@ -69,11 +69,21 @@ struct metadata_response {
     void decode(iobuf buf, api_version version) {
         data.decode(std::move(buf), version);
     }
-
-    friend std::ostream&
-    operator<<(std::ostream& os, const metadata_response& r) {
-        return os << r.data;
-    }
 };
 
 } // namespace kafka
+
+template<>
+struct fmt::formatter<kafka::metadata_response> {
+    template<typename ParseContext>
+    constexpr auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+        return ctx.begin();
+    }
+
+    template<typename FormatContext>
+    auto format(
+      [[maybe_unused]] const kafka::metadata_response& v,
+      FormatContext& ctx) const -> decltype(ctx.out()) {
+        return fmt::format_to(ctx.out(), "{}", v.data);
+    }
+};