Allow ping passthrough for descriptions too

proxy/src/main/java/com/velocitypowered/proxy/config/PingPassthroughMode.java

@@ -3,5 +3,6 @@ package com.velocitypowered.proxy.config;
 public enum PingPassthroughMode {
   DISABLED,
   MODS,
+  DESCRIPTION,
   ALL
 }

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -96,6 +96,9 @@ public class VelocityConfiguration extends AnnotatedConfig implements ProxyConfi
       "                 The first server in your try list (or forced host) with a mod list will be",
       "                 used. If no backend servers can be contacted, Velocity will not display any",
       "                 mod information.",
+      "- \"description\": Uses the description and mod list from the backend server. The first",
+      "                 server in the try (or forced host) list that responds is used for the",
+      "                 description and mod list.",
       "- \"all\":         Passes everything from the backend server into the response. The Velocity",
       "                 configuration is used if no servers could be contacted."
   })

proxy/src/main/java/com/velocitypowered/proxy/connection/client/StatusSessionHandler.java

@@ -97,6 +97,24 @@ public class StatusSessionHandler implements MinecraftSessionHandler {
           }
           return fallback;
         });
+      case DESCRIPTION:
+        return pingResponses.thenApply(responses -> {
+          // Find the first non-fallback. If it includes a modlist, add it too.
+          for (ServerPing response : responses) {
+            if (response == fallback) {
+              continue;
+            }
+
+            return new ServerPing(
+                fallback.getVersion(),
+                fallback.getPlayers().orElse(null),
+                response.getDescription(),
+                fallback.getFavicon().orElse(null),
+                response.getModinfo().orElse(null)
+            );
+          }
+          return fallback;
+        });
       default:
         // Not possible, but covered for completeness.
         return CompletableFuture.completedFuture(fallback);