### Godot version

master

### System information

Godot v4.2.beta (0ea75d77c) - Windows 10.0.22621 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2070 (NVIDIA; 31.0.15.3598) - Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz (12 Threads)

### Issue description

When any of the Import, Filesystem, Node, or History docks are floating, changing an editor feature crashes the engine.
Changing any setting or selecting a different profile triggers it.

This is because `EditorNode::_feature_profile_changed` assumes the docks are in a `TabContainer`, and if they are floating they aren't in one.


### Steps to reproduce

Make any of these docks floating: Import, Filesystem, Node, or History
Open Editor Features (Editor -> Manage Editor Features...)
Make a profile (if you have none) or change a setting on the existing profile

### Minimal reproduction project

n/a
if (!scene_root->is_inside_tree()) {
		return; 
	}
	List<Ref<Theme>> preview_themes;
	switch (p_mode) {
		case CanvasItemEditor::THEME_PREVIEW_PROJECT:
			preview_themes.push_back(ThemeDB::get_singleton()->get_project_theme());
			break;
		case CanvasItemEditor::THEME_PREVIEW_EDITOR:
			preview_themes.push_back(get_editor_theme());
			break;
		default:
			break;
	}
	preview_themes.push_back(ThemeDB::get_singleton()->get_default_theme());
	ThemeContext *preview_context = ThemeDB::get_singleton()->get_theme_context(scene_root);
	if (preview_context) {
		preview_context->set_themes(preview_themes);
	} else {
		ThemeDB::get_singleton()->create_theme_context(scene_root, preview_themes);
	}
}
void EditorNode::_notification(int p_what) {