(maint) Cleanup uses of r-value references in parameters.

Remove r-value references used in parameters to favor pass-by-value.
Passing by-value gives the caller the option to move or copy depending
on whether or not an r-value is provided and the callee moves the
parameter accordingly.
(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.
(CFACT-134) Hide duplicated facts in cfacter output.

Hiding duplicated facts that are now respresented in structured data.
The facts are still present, just hidden from cfacter output by default.
(CFACT-134) Implement identity structured fact and hide id/gid.

Implementing the identity structured fact and hide the id/gid facts from
command line output by default.
(CFACT-134) Add OSX info to os structured fact.

Adding OSX build, product, and version to the os structured fact and
hide the macosx_* facts from output by default.
(CFACT-134) Add system_profiler structured fact.

Add system_profiler structured fact and remove the existing system
profiler related facts from the output by default.
(CFACT-134) Add dmi structured fact and cleanup DMI facts.

Adding a dmi structured fact that represents DMI data (TODO: come up
with a better name than "dmi"?).

Also hidding the existing DMI facts from default command line output.
Merge pull request #188 from peterhuene/facts/cleanup

(CFACT-134) General cleanup of cfacter command line output.

* peterhuene/facts/cleanup:
  (CFACT-134) Add dmi structured fact and cleanup DMI facts.
  (CFACT-134) Add system_profiler structured fact.
  (CFACT-134) Add OSX info to os structured fact.
  (CFACT-134) Implement identity structured fact and hide id/gid.
  (CFACT-134) Hide duplicated facts in cfacter output.
  (maint) Remove unused cycle detection in fact resolvers.
  (maint) Add missing doc comments.
  (maint) Remove unused "resolve" parameter from collection methods.
  (maint) Cleanup uses of r-value references in parameters.