### Godot version

Godot 4.0.3

### System information

Windows 10 64 bits NVIDIA GeForce GTX 1060

### Issue description

Ctrl+K is a shortcut normally used to comment out the current line. It works in the shader editor, but for some reason, it doesn't if your shader has the `.gdshaderinc` extension (aka it's a shader include). Shader Includes are the same language, we should be able to use that feature.

### Steps to reproduce

Create a `.gdshaderinc` file. Write some code in it. Observe you can't use Ctrl+K to comment out lines.

### Minimal reproduction project

[CommentLinesShaderInc.zip](https://github.com/godotengine/godot/files/11739881/CommentLinesShaderInc.zip)

#include "text_shader_editor.h"
#include "core/version_generated.gen.h"
#include "editor/editor_node.h"
#include "editor/editor_scale.h"
#include "editor/editor_settings.h"
#include "editor/filesystem_dock.h"
#include "editor/project_settings_editor.h"
#include "scene/gui/split_container.h"
#include "servers/rendering/shader_preprocessor.h"
#include "servers/rendering/shader_types.h"
Dictionary GDShaderSyntaxHighlighter::_get_line_syntax_highlighting_impl(int p_line) {