Fix some missing categories in visual shader nodes

[AThousandShips]

Confirmed these with:

diff --git a/scene/resources/visual_shader.h b/scene/resources/visual_shader.h
index 09ea9a8890..3a7b3ea09c 100644
--- a/scene/resources/visual_shader.h
+++ b/scene/resources/visual_shader.h
@@ -366,7 +366,7 @@ public:

        virtual String get_warning(Shader::Mode p_mode, VisualShader::Type p_type) const;

-       virtual Category get_category() const;
+       virtual Category get_category() const = 0;

        VisualShaderNode();
 };
@@ -468,6 +468,8 @@ public:
        bool _is_highend() const;
        void _set_option_index(int p_op, int p_index);

+       virtual Category get_category() const override { return CATEGORY_SPECIAL; }
+
        int get_option_index(int p_op) const;
 };

• Fixes: Visual shader warning "Clamp is missing a category" when opening a project and/or adding a node in visual shader editor. #89152

[AThousandShips]

These were redundant as the parent type already does this

[AThousandShips]

Was redundant

[AThousandShips]

I'm unsure exactly what category to assign these to

[Geometror]

We might want to add a new category for SDF nodes in the future. Or we just use CATEGORY_TEXTURES or CATEGORY_SPECIAL, at least that's what I would do for now.

[akien-mga]

Thanks!

[AThousandShips]

Thank you!