Make ospack recipe output list of packages and files

Developers would benefit from pregenerated listings to avoid downloading and unpacking all the ospacks just to check the version of a shipped package or the availability of a file.

Being able to rely on pregenerated package and file listings would help speed up the checks needed by T5042 to identify which images are affected.

Signed-off-by: Andrew Lee (李健秋) andrew.lee@collabora.co.uk