Add @tag directive to fusion. (#6341)

Author: michaelstaib

src/HotChocolate/Core/src/Abstractions/WellKnownDirectives.cs

@@ -1,16 +1,72 @@
 namespace HotChocolate;
 
+/// <summary>
+/// Provides well-known directive names.
+/// </summary>
 public static class WellKnownDirectives
 {
+    /// <summary>
+    /// The name of the @skip directive.
+    /// </summary>
     public const string Skip = "skip";
+
+    /// <summary>
+    /// The name of the @include directive.
+    /// </summary>
     public const string Include = "include";
+
+    /// <summary>
+    /// The name of the @defer directive.
+    /// </summary>
     public const string Defer = "defer";
+
+    /// <summary>
+    /// The name of the @stream directive.
+    /// </summary>
     public const string Stream = "stream";
+
+    /// <summary>
+    /// The name of the @oneOf directive.
+    /// </summary>
     public const string OneOf = "oneOf";
+
+    /// <summary>
+    /// The name of the if directive argument.
+    /// </summary>
     public const string IfArgument = "if";
+
+    /// <summary>
+    /// The name of the label directive argument.
+    /// </summary>
     public const string LabelArgument = "label";
+
+    /// <summary>
+    /// The name of the initialCount directive argument.
+    /// </summary>
     public const string InitialCount = "initialCount";
+
+    /// <summary>
+    /// The name of the @deprecated directive.
+    /// </summary>
     public const string Deprecated = "deprecated";
+
+    /// <summary>
+    /// The name of the deprecated directive argument.
+    /// </summary>
     public const string DeprecationReasonArgument = "reason";
+
+    /// <summary>
+    /// The deprecation default reason.
+    /// </summary>
     public const string DeprecationDefaultReason = "No longer supported.";
+
+    /// <summary>
+    /// The name of the @tag directive.
+    /// </summary>
+    public const string Tag = "tag";
+    
+    /// <summary>
+    /// The name of the @tag argument name.
+    /// </summary>
+    public const string Name = "name";
 }

src/HotChocolate/Core/src/Types/Internal/TypeDependencyHelper.cs

@@ -162,10 +162,26 @@ public static void CollectDependencies(
         DirectiveTypeDefinition definition,
         ICollection<TypeDependency> dependencies)
     {
+        if (definition.HasDependencies)
+        {
+            foreach (var dependency in definition.Dependencies)
+            {
+                dependencies.Add(dependency);
+            }
+        }
+        
         if (definition.HasArguments)
         {
             foreach (var argument in definition.Arguments)
             {
+                if (argument.HasDependencies)
+                {
+                    foreach (var dependency in argument.Dependencies)
+                    {
+                        dependencies.Add(dependency);
+                    }
+                }
+                
                 if (argument.Type is not null)
                 {
                     dependencies.Add(new(