src/vs/workbench/services/themes/common/themeConfiguration.ts/updateFileIconThemeConfigurationSchemas
export function updateFileIconThemeConfigurationSchemas(themes: IWorkbenchFileIconTheme[]) {
	fileIconThemeSettingSchema.enum!.splice(1, Number.MAX_VALUE, ...themes.map(t => t.settingsId));
	fileIconThemeSettingSchema.enumItemLabels!.splice(1, Number.MAX_VALUE, ...themes.map(t => t.label));
	fileIconThemeSettingSchema.enumDescriptions!.splice(1, Number.MAX_VALUE, ...themes.map(t => t.description || ''));

	configurationRegistry.notifyConfigurationSchemaUpdated(themeSettingsConfiguration);
}