### 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)

shader_editor->get_text_editor()->paste();
		} break;
		case EDIT_SELECT_ALL: {
			shader_editor->get_text_editor()->select_all();
		} break;
		case EDIT_MOVE_LINE_UP: {
			shader_editor->move_lines_up();
		} break;
		case EDIT_MOVE_LINE_DOWN: {
			shader_editor->move_lines_down();
		} break;
		case EDIT_INDENT: {
			if (shader.is_null()) {
				return;
			}
			shader_editor->get_text_editor()->indent_lines();
		} break;
		case EDIT_UNINDENT: {
			if (shader.is_null()) {
				return;
			}
			shader_editor->get_text_editor()->unindent_lines();
		} break;
		case EDIT_DELETE_LINE: {
			shader_editor->delete_lines();
		} break;
		case EDIT_DUPLICATE_SELECTION: {
			shader_editor->duplicate_selection();
		} break;
		case EDIT_TOGGLE_WORD_WRAP: {