src/vs/workbench/contrib/terminal/browser/terminalIcon.ts/getIconId
export function getIconId(accessor: ServicesAccessor, terminal: ITerminalInstance | IExtensionTerminalProfile | ITerminalProfile): string {
	if (!terminal.icon || (terminal.icon instanceof Object && !('id' in terminal.icon))) {
		return accessor.get(ITerminalProfileResolverService).getDefaultIcon().id;
	}
	return typeof terminal.icon === 'string' ? terminal.icon : terminal.icon.id;
}