Add AllPrimitives and AllPrimitivesWithKeyManager

[theory]

These new methods on the keyset handle complement Primitives and PrimitivesWithKeyManager, but return all primitives, not just enabled primitives. This can be useful for key implementations to display information about key parameters, but should not be used to create sets for encryption duties, since only enabled keys should be used for encryption.

Done by adding a filter function to the private primitives method, and having Primitives and PrimitivesWithKeyManager use it to filter for enabled keys, while AllPrimitives and AllPrimitivesWithKeyManager don't filter. This keeps the code changes to a minimum. Also: add test to ensure that disabled keys are included in the All methods but excluded in the non-All methods.

Requires disabling the check for enabled keys in primitiveset; should probably change it to allow the adding of other keys through a separate method or something, but I wanted to get some feedback and discussion going before I dove into that, so simply commenting out that check (and the corresponding test) for now.

See discussion in #14 for some of the background on this proposal.

[juergw]

I don't think we want to add this. Sorry.

We do have plans to extend the API of keyset.Handle, similar to what is already possible in Java, see: https://javadoc.io/static/com.google.crypto.tink/tink/1.13.0/com/google/crypto/tink/KeysetHandle.html

But since this is a bigger redesign, I don't think we will accept pull requests for this until the majority of the re-work is done.

[theory]

I don't think we want to add this. Sorry.

Okay, I'll keep my ugly hack for now, then.

We do have plans to extend the API of keyset.Handle, similar to what is already possible in Java, see: https://javadoc.io/static/com.google.crypto.tink/tink/1.13.0/com/google/crypto/tink/KeysetHandle.html

Do you mean something like getAt, assuming that it returns keys regardless of their status? I think that would be fine for my use case.