[perf] Restart without Xdebug before the container is built

[SanderMuller]

When Xdebug is loaded, XdebugHandler restarts Rector without it. The check ran in ConsoleApplication::doRun(), after bin/rector had loaded the configs and built the container. The restarted process then did all of that work again.

The check now runs in bin/rector, right after the autoloaders and before the configs load. It still calls setPersistent() and is still skipped with --xdebug, so the behaviour from #5544 stays the same. Workers still start without Xdebug.

I measured on an M4 Pro with Herd's PHP 8.5 and Xdebug in its default develop mode. All runs used a warm cache and --dry-run, with the two sides interleaved:

• rector-src src/Console, 10 runs per side: CPU median 1.15 s before, 0.76 s after. The ranges, 1.06 to 1.29 s and 0.71 to 0.83 s, do not overlap.
• Shopware v6.7.6.2 with its own rector.php, 10 runs per side: CPU median 4.98 s before, 4.15 s after. The machine was busy, so the ranges overlap. 7 of the 10 pairs were faster after the change.
• Without Xdebug there is no restart, and there was no difference: 0.43 s and 0.46 s CPU.

Each run gave the same output on both sides.

-v, the version alias, used to return before the check. With Xdebug loaded, it now restarts first and then prints the same version.

[TomasVotruba]

Seems valid, the sooner we spot this the better 👍