[TASK] Introduce PHPStan for level 1

Levels can be raised step by step in follow-ups

We need to get rid of the outdated XClass extension, but don't have a replacement yet, that is why I left it in for now.

run with
Build/Scripts/runTests.sh -s phpstan

Generate baseline with
Build/Scripts/runTests.sh -s phpstanBaseline

Build/Scripts/runTests.sh

@@ -297,9 +297,9 @@ case ${TEST_SUITE} in
         ;;
     rector)
         if [ "${CGLCHECK_DRY_RUN}" -eq 1 ]; then
-            COMMAND=(php -dxdebug.mode=off .Build/bin/rector -n --clear-cache "$@")
+            COMMAND=(php -dxdebug.mode=off .Build/bin/rector -n --config=Build/rector/rector.php --clear-cache "$@")
         else
-            COMMAND=(php -dxdebug.mode=off .Build/bin/rector --clear-cache "$@")
+            COMMAND=(php -dxdebug.mode=off .Build/bin/rector --config=Build/rector/rector.php --clear-cache "$@")
         fi
         ${CONTAINER_BIN} run ${CONTAINER_COMMON_PARAMS} --name rector-${SUFFIX} -e COMPOSER_CACHE_DIR=.Build/.cache/composer -e COMPOSER_ROOT_VERSION=${COMPOSER_ROOT_VERSION} ${IMAGE_PHP} "${COMMAND[@]}"
         SUITE_EXIT_CODE=$?

rector.php → Build/rector/rector.php

@@ -27,12 +27,12 @@
 
 return RectorConfig::configure()
     ->withPaths([
-        __DIR__ . '/.',
+        __DIR__ . '/../../.',
     ])
-    ->withImportNames(true, true, false, true)
+    ->withImportNames(importShortClasses: false, removeUnusedImports: true)
     ->withPhpSets()
     ->withAutoloadPaths([
-        __DIR__ . '/.Build/vendor/autoload.php',
+        __DIR__ . '/../../.Build/vendor/autoload.php',
     ])
     ->withSets([
         Typo3SetList::CODE_QUALITY,
@@ -58,6 +58,6 @@
         ReturnNeverTypeRector::class => [
             // We want to keep the ResponseInterface return type of indexAction() to be compatible
             // with the specification, although we just throw an exception for demonstration purpose.
-            __DIR__ . '/Classes/Controller/ErrorController.php',
+            __DIR__ . '/../../Classes/Controller/ErrorController.php',
         ],
     ]);