Feature gate awareness for registries/packaging tooling

[vados-cosmonic]

During the packaging SIG meeting yesterday (and the JS meeting) the idea of registries/packaging tooling being feature gate aware came up.

While this can take on many meanings, the primary one was the (possible) need to be able to specify certain features for packages.

There's also a conversation going on right now related to how feature gates should be handled, and the idea of a "target version" might also be a relevant idea (i.e. a settable parameter when retrieving/doing things with packages).

I think the simple answer here (which might be good enough) is that this is just a version resolution problem (this is somewhat different if the "target version" idea comes to fruition), and all items under all features should be returned regardless.