Refactor Puppet::Util::Feature.add to expose caching options

The "add" method of Puppet::Util::Feature has a couple of different caching behaviours, which should instead be explicitly exposed through the options hash or via multiple methods.

Prior to #14822:

• blocks get immediately run and the result cached
• test results get cached on the first query to the feature

After #14822:

• blocks get immediately run and the result cached
• tests, positive results get cached on the first query to the feature

The interface should probably offer the ability to always cache, positive or negative cache and to never cache.