Refactor libraryCardsEnabled method to AccountCapabilities class.

[demiankatz]

This is a first step toward decoupling library cards enabled checks from user row objects. We need to do this in order to begin moving more logic into the UserCardService, which in turn is needed to complete #3625.

I don't think there's any way to do this that isn't somewhat messy. I welcome suggestions for better approaches.

TODO:

• Merge Use UserEntityInterface/UserService in LoginTokenManager. #3631 and Use DbTableAwareTrait in UserService. #3632 before this
• Merge Refactor AuthManager to use UserService and UserEntityInterface #3636 before this
• Merge Expand use of UserEntityInterface in console commands #3638 before this
• Update changelog when merging (changes to \VuFind\Config\AccountCapabilities constructor/auth property; changes to \VuFind\Db\Row\User constructor)

[demiankatz]

I think this is now ready for review. As discussed elsewhere (probably on Slack) it might make sense to move the inPrivacyMode method into AccountCapabilities as well... but this will only strengthen the existing circular dependencies, so I'm not sure if it's a good idea. Either way, I think that's a separate matter that can be handled outside of this current PR.

[EreMaijala]

Based on the description I was expecting something much more messy than this. Looks good to me!

[demiankatz]

Based on the description I was expecting something much more messy than this. Looks good to me!

It started out a lot messier before I split big chunks of it off into separate PRs and simplified everything. :-)