Add a /geyser ping command (#4131)

* Init: Add /geyser ping command

* Block just console execution, not everything but console senders

* Use RTT as that seems to vary less wildly compared to getPing()

* Cleanup, use lang strings

* Add ping() method to GeyserConnection in api

* Update to cloud changes

api/src/main/java/org/geysermc/geyser/api/connection/GeyserConnection.java

@@ -132,4 +132,9 @@ public interface GeyserConnection extends Connection, CommandSource {
     @Deprecated
     @NonNull
     Set<String> fogEffects();
+
+    /**
+     * Returns the current ping of the connection.
+     */
+    int ping();
 }