[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.