Navigation selector.
type NavsField<T extends string = string> = TitledHandle<T> | TitledHandle<T>[];
type MainNav = NavsField<"main">;
// Result: {
// handle: "main";
// title: string;
// } | {
// handle: "main";
// title: string;
// }[]
type AllNavigations = NavsField<"main" | "footer">;
// Result: {
// handle: "main" | "footer";
// title: string;
// } | {
// handle: "main" | "footer";
// title: string;
// }[]