Before this commit, we did not have guardian checks in place to determine if a
topic's title associated with a user badge should be displayed or not.
This means that the topic title of topics with restricted access
could be leaked to anon and users without access if certain conditions
are met. While we will not specify the conditions required, we have internally
assessed that the odds of meeting such conditions are low.
With this commit, we will now apply a guardian check to ensure that the
current user is able to see a topic before the topic's title is included
in the serialized object of a `UserBadge`.
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
BasicUserSerializer contains enough information for the badges page,
while UserSerializer issues ~100 SQL queries on the fly when serializing
the field without preloading.
