Upgrade to xdebug-handler 2 (#9832)

This adds support for Xdebug3 modes and changes the default behaviour
from always restarting if Xdebug is loaded, to only restarting if Xdebug
is active.

Xdebug is considered active if it is loaded, and for Xdebug3, if it is
running in a mode other than `xdebug.mode=off`.

tests/Composer/Test/ApplicationTest.php

@@ -13,6 +13,7 @@
 namespace Composer\Test;
 
 use Composer\Console\Application;
+use Composer\XdebugHandler\XdebugHandler;
 use Symfony\Component\Console\Output\OutputInterface;
 
 class ApplicationTest extends TestCase
@@ -54,7 +55,7 @@ class ApplicationTest extends TestCase
         $outputMock->expects($this->at($index++))
             ->method("write");
 
-        if (extension_loaded('xdebug')) {
+        if (XdebugHandler::isXdebugActive()) {
             $outputMock->expects($this->at($index++))
                 ->method("getVerbosity")
                 ->willReturn(OutputInterface::VERBOSITY_NORMAL);