[php-src] Issue #20336: Observer API: Function invocation tracking

Issue: https://github.com/php/php-src/issues/20336 Author: th3r0b0t ### Description ## Problem AFAIK one of things Observer API fixes is the old problem with overriding zend_execute_ex forces VM to go into stack execution mode. Forgive me for I’m a newbie in the field but I see the zend_observer_fcall_handlers’s begin and end handlers as events fired independently; These handlers are given only a zend_execute_data with nothing (AFAICT) to be used as unique identifier. Memory address of zend_execute_data being reused, hence not suitable either. I need a way to match the data between begin and end handler for an invocation. ## Requested Feature or guidance: If zend_execute_data could have something like op_array.reserved[] but per-call or any unique property, it would solve the problem.