Allow ServerboundChangeGameModePacket if player has /gamemode permissions (#13507)

Author: Warriorrrr

paper-server/patches/sources/net/minecraft/server/network/ServerGamePacketListenerImpl.java.patch

@@ -2498,7 +2498,7 @@
          if (this.player.isModelPartShown(PlayerModelPart.HAT) != wasHatShown) {
              this.server.getPlayerList().broadcastAll(new ClientboundPlayerInfoUpdatePacket(ClientboundPlayerInfoUpdatePacket.Action.UPDATE_HAT, this.player));
          }
-@@ -2082,7 +_,7 @@
+@@ -2082,21 +_,21 @@
                  packet.difficulty().getDisplayName()
              );
          } else {
@@ -2507,7 +2507,14 @@
          }
      }
 
-@@ -2096,7 +_,7 @@
+     @Override
+     public void handleChangeGameMode(final ServerboundChangeGameModePacket packet) {
+         PacketUtils.ensureRunningOnSameThread(packet, this, this.player.level());
+-        if (!GameModeCommand.PERMISSION_CHECK.check(this.player.permissions())) {
++        if (!GameModeCommand.PERMISSION_CHECK.check(this.player.permissions()) && !this.player.getBukkitEntity().hasPermission("minecraft.command.gamemode")) { // Paper - add permission check
+             LOGGER.warn(
+                 "Player {} tried to change game mode to {} without required permissions",
+                 this.player.getGameProfile().name(),
                  packet.mode().getShortDisplayName().getString()
              );
          } else {