tests/functional: add 'archive_extract' to QemuBaseTest

tests/functional: add 'archive_extract' to QemuBaseTest

This helper wrappers archive.archive_extract, forcing the use of the
scratch directory, to ensure any extracted files are cleaned at test
termination. If a specific member is requested, then the path to the
extracted file is also returned.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20241217155953.3950506-23-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>