fixExport() produces invalid FQCN on PHP 8.2

[IonBazan]

fixExport() introduced in #17 does not work correctly on PHP 8.2, where var_export() behaviour was changed:

1) ProxyManagerTest\Functional\MultipleProxyGenerationTest::testCanGenerateMultipleDifferentProxiesForSameClass with data set "php81defaults" (ProxyManagerTestAsset\ClassWithPhp81Defaults Object (...))
Error: Class "P\roxyManagerTestAsset\FooEnum" not found

proxy-manager-lts/tests/ProxyManagerTest/Functional/MultipleProxyGenerationTest.php:103

2) ProxyManagerTest\Functional\RemoteObjectFunctionalTest::testXmlRpcMethodCalls with data set "when using php8.1 defaults" ('ProxyManagerTestAsset\RemoteP...erface', 'php81Defaults', array(), array(ProxyManagerTestAsset\RemoteProxy\FooEnum Object (...), stdClass Object ()), 200)
Error: Class "P\roxyManagerTestAsset\RemoteProxy\FooEnum" not found

proxy-manager-lts/tests/ProxyManagerTest/Functional/RemoteObjectFunctionalTest.php:107

3) ProxyManagerTest\Functional\RemoteObjectFunctionalTest::testJsonRpcMethodCalls with data set "when using php8.1 defaults" ('ProxyManagerTestAsset\RemoteP...erface', 'php81Defaults', array(), array(ProxyManagerTestAsset\RemoteProxy\FooEnum Object (...), stdClass Object ()), 200)
Error: Class "P\roxyManagerTestAsset\RemoteProxy\FooEnum" not found

proxy-manager-lts/tests/ProxyManagerTest/Functional/RemoteObjectFunctionalTest.php:131

As you can see, it produces \P\roxyManagerTestAsset\FooEnum instead of \ProxyManagerTestAsset\FooEnum.

Ref: php/php-src#8232
Ref: php/php-src#8233