PUP-1772 Change api for Puppet::Util::Profiler#profile to public

This patch changes the YardDoc annotations so that the class
'Puppet::Util::Profiler' is now public, and its method #profile
is also public.

The remaining methods are still marked as private, as they
aren't really needed by most external consumers.

Signed-off-by: Ken Barber <ken@bob.sh>