PHP 8.1: fix deprecation notices / PharData::__construct()

This fixes all relevant calls to the PHP native `PharData::__construct()` method.

The second parameter of this method is the _optional_ `$flags` parameter which expects an `int` of flags to be passed to the `Phar` parent class `RecursiveDirectoryIterator`.
Fixed by passing the default value for the `$flags` parameter as per the `RecursiveDirectoryIterator::__construct()` method.

The third parameter of the method is the _optional_ `$alias` parameter which expects an `string`.
Fixed by passing an empty string.

Fixes various notices along the lines of:
```
Deprecation triggered by Composer\Test\Package\Archiver\ArchiveManagerTest::testArchiveTar:
PharData::__construct(): Passing null to parameter #2 ($flags) of type int is deprecated

Stack trace:
0 [internal function]: Symfony\Bridge\PhpUnit\DeprecationErrorHandler->handleError(8192, '...', '...', 55)
1 src/Composer/Package/Archiver/PharArchiver.php(55): PharData->__construct('...', NULL, NULL, 2)
2 src/Composer/Package/Archiver/ArchiveManager.php(193): Composer\Package\Archiver\PharArchiver->archive('...', '...', '...', Array, false)
3 tests/Composer/Test/Package/Archiver/ArchiveManagerTest.php(65): Composer\Package\Archiver\ArchiveManager->archive(Object(Composer\Package\CompletePackage), '...', '...')
...
```

Additionally, this fixes three `preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated` notices.

Refs:
* https://www.php.net/manual/en/phardata.construct.php
* https://www.php.net/manual/en/recursivedirectoryiterator.construct.php

src/Composer/Package/Archiver/PharArchiver.php

@@ -52,7 +52,12 @@ public function archive($sources, $target, $format, array $excludes = array(), $
                 $target = $filename . '.tar';
             }
 
-            $phar = new \PharData($target, null, null, static::$formats[$format]);
+            $phar = new \PharData(
+                $target,
+                FilesystemIterator::KEY_AS_PATHNAME | FilesystemIterator::CURRENT_AS_FILEINFO,
+                '',
+                static::$formats[$format]
+            );
             $files = new ArchivableFilesFinder($sources, $excludes, $ignoreFilters);
             $filesOnly = new ArchivableFilesFilter($files);
             $phar->buildFromIterator($filesOnly, $sources);