Improve handling of generic C# types

- Create CSharpScript for generic C# types.
  - `ScriptPathAttributeGenerator` registers the path for the generic type definition.
  - `ScriptManagerBridge` lookup uses the generic type definition that was registered by the generator.
  - Constructed generic types use a virtual `csharp://` path so they can be registered in the map and loaded as if there was a different file for each constructed type, even though they all share the same real path.
  - This allows getting the base type for a C# type that derives from a generic type.
- Shows base scripts in the _Add Node_ and _Create Resource_ dialogs even when they are generic types.
  - `get_global_class_name` implementation was moved to C# and now always returns the base type even if the script is not a global class (this behavior matches GDScript).
- Create `CSharpScript::TypeInfo` struct to hold all the type information about the C# type that corresponds to the `CSharpScript`, and use it as the parameter in `UpdateScriptClassInfo` to avoid adding more parameters.

modules/mono/editor/Godot.NET.Sdk/Godot.SourceGenerators/ScriptPathAttributeGenerator.cs

@@ -54,9 +54,7 @@ namespace Godot.SourceGenerators
                 )
                 .Where(x =>
                     // Ignore classes whose name is not the same as the file name
-                    Path.GetFileNameWithoutExtension(x.cds.SyntaxTree.FilePath) == x.symbol.Name &&
-                    // Ignore generic classes
-                    !x.symbol.IsGenericType)
+                    Path.GetFileNameWithoutExtension(x.cds.SyntaxTree.FilePath) == x.symbol.Name)
                 .GroupBy(x => x.symbol)
                 .ToDictionary(g => g.Key, g => g.Select(x => x.cds));
 
@@ -160,6 +158,8 @@ namespace Godot.SourceGenerators
                 first = false;
                 sourceBuilder.Append("typeof(");
                 sourceBuilder.Append(qualifiedName);
+                if (godotClass.Key.IsGenericType)
+                    sourceBuilder.Append($"<{new string(',', godotClass.Key.TypeParameters.Count() - 1)}>");
                 sourceBuilder.Append(")");
             }