Add redemption tokens which are good for n license creations

[ezekg]

Will allow to pre-generate a list of redemption tokens, good for 1 redemption each, that can be distributed with physical products, which can be used to create a real license upon redemption.

[ezekg]

Another use-case popped up: allowing client-side license creation, but nothing else. Would only work with unprotected policies, similar to user license creation. Right now the only alternative is a product token with a singular license.create permission. But right now, custom permissions are only available to Ent customers.

Ref: https://github.com/orgs/keygen-sh/discussions/159#discussioncomment-11054730