[Proposal]: once function

### Function Signature

function once any>(fn: T): T;

### Motivation

once restricts a function to be invoked only once. Subsequent calls return the cached result:
```ts
const initialize = once(() => {
console.log('Loading...');
return { ready: true };
});

initialize(); // Logs: 'Loading...', returns { ready: true }
initialize(); // No log, returns { ready: true }
```

Benefits:
- Useful for expensive operations like initialization or API calls.
- Ensures idempotency for setup functions.
- Simple and lightweight memoization for single invocation.