(maint) Remove unused "resolve" parameter from collection methods.

With the resolver refactoring, this parameter is no longer used.
Removing it to simplify code.
(maint) Add missing doc comments.

Adding some missing doc comments that slipped through CI.
(maint) Remove unused cycle detection in fact resolvers.

Because of the way we need to force a resolver to resolve when a fact it
is responsible is added to the collection (i.e. from a custom or
external fact), we remove a resolver from the collection prior to doing
the resolve.

As a result, the old cycle detection isn't used because the resolver
isn't in the collection during resolution.  Instead of throwing a cycle
detection, we break the cycle and return nullptr for the requested fact.