This PR adds a new jit_debugging_enabled ini setting that allows you to disable some of the optimizations that we have added. When this is enabled you will be able to do JIT debugging even if you don't initially connect to any client by starting a connection using the xdebug_connect_to_client and xdebug_break functions or when an error or exception is raised. If you enable it then the performance gain is much smaller, instead of improving performance by 97% you will improve it by 60% (not bad in any case)

With this disabled I wanted to be able to disable even more operations so that we could save even more time but I found out that the only significant thing that we could add was not disabling the opcache optimizer, the other main source of overhead is the addition of the observer functions but this needs to be set up at the module initialization level, so we cannot actually disable it for each request depending on whether we connect or not

And the opcache optimizer is really only relevant for cgi/fpm processes, not cli processes, as opcache is not really useful for single use CLI commands and is usually disabled there, so I did not manage to really improve the current optimization by much

But what I was able to do is to get the vast majority of tests which had been marked as XFAIL to pass by setting this ini setting to enabled. There are still a couple which are still failing and where I need to take a deeper look. I also managed to get a few of the tests which had been skipped to pass by using this new setting or by changing some basic settings of the test setup