Check source permission level before selector permission (#9147)

In some situations, such as execution of a function by an advancement as
part of its reward, a command source stack may have a backing source of
a ServerPlayer which may lack the entity selector permission and have an
explicit permission level that should allow the use of entity selectors,
through CommandSourceStack#withPermission.

We now check if the permission level of the command source stack is
sufficient for entity selectors _before_ checking if the source is a
player and if they have the requisite permission.

This means that an operator permission level of 2 will always override
the Forge entity selector permission.

Fixes #9137

src/main/java/net/minecraftforge/common/ForgeHooks.java

@@ -1650,10 +1650,14 @@ public class ForgeHooks
 
     public static boolean canUseEntitySelectors(SharedSuggestionProvider provider)
     {
-        if (provider instanceof CommandSourceStack source && source.source instanceof ServerPlayer player)
+        if (provider.hasPermission(Commands.LEVEL_GAMEMASTERS))
+        {
+            return true;
+        }
+        else if (provider instanceof CommandSourceStack source && source.source instanceof ServerPlayer player)
         {
             return PermissionAPI.getPermission(player, ForgeMod.USE_SELECTORS_PERMISSION);
         }
-        return provider.hasPermission(Commands.LEVEL_GAMEMASTERS);
+        return false;
     }
 }