[php-src] Issue #20638: Feature request: add syntax to prevent preprocessing

Issue: https://github.com/php/php-src/issues/20638
Author: woodholly

### Description

The Problem:

```php
$logger->debug('action', [
    'user' => $user->toArray(),
    'trace' => debug_backtrace(),
]);
```

That debug_backtrace() runs every time, eats CPU, RAM, even when debug is off. PHP evaluates arguments before the call. Always.

Current Workarounds Suck:

```php
if ($logger->isHandling(Logger::DEBUG)) {
    $logger->debug('action', $expensiveStuff);
}
```
Closure - can't capture locals cleanly:
```php
$logger->debug('action', fn() => ['user' => $user, 'x' => $x, 'y' => $y]);
```

Short-circuit - inverted logic, looks like a bug, globals:
```php
$noDebug or $logger->debug('action', $expensive);
```

So, last hope - build postprocessor to remove debug ? - are we writing C?

Proposed: lazy Keyword

```php
function debug(string $msg, lazy array $context = []): void {
    if (!$this->enabled) return;  // $context never evaluated
    $this->write($msg, $context); // evaluated here
}
```

Usage stays clean:

```php
$logger->debug('action', ['trace' => debug_backtrace()]);
```

Other Use Cases
```php
assert(lazy $obj->isValid(), lazy $obj->getErrorMessage());
$cache->remember('key', lazy $this->heavyQuery());
```

Kotlin, Swift, Scala, Rust all have this. PHP doesn't.