Binaries in the archive root are not extracted #59

Description

PharAwareArchive::extract() cannot extract a binary from the archive root. For a zip that contains LICENSE and rr at the top level, extraction fails with:

RecursiveDirectoryIterator::__construct(phar:///tmp/.../rr.zip/rr): Failed to open directory: operation failed

extract() reopens the archive with $this->open($this->archive). $this->archive is the PharData iterator itself, so its getPathname() returns the current entry, i.e. the first file in the archive, not the archive. Only that first entry is searched:

• if it is a directory, the files inside it are found;
• if it is a file, the reopen fails.

Current RoadRunner archives put everything in one top-level directory (roadrunner-<version>-<os>-<arch>/rr), which is the only reason extraction works today. A flat archive, or a binary outside the first top-level entry, cannot be installed.

Steps to reproduce

1. Remove #[Skip] from PharAwareArchiveTest::extractFindsBinaryInArchiveRoot.
2. Run vendor/bin/testo --filter=extractFindsBinaryInArchiveRoot.

Additional context

Archive handling may be replaced by DLoad in #49, in which case this code goes away.