We want to be able to load aliases even in cases where there is no need
to load all the rest of the related info for an artist, such as in tag pages.
That means it makes sense to extract load_aliases as a separate
method that can be called by load_related_info.

While we only use this in artists right now, there's no big reason that it
needs to be that way. As such, this moves it out of Data::Artist into the
Alias role so it can be used by other entities as well.

The aliases and primary_alias properties added to Artist alone
will be useful for other entities as well, so this extracts them into
a new Entity::Role::Alias role and adds the role to all the
entity types that support aliases.

We already translate instruments, so showing a primary alias for them
would just be redundant.

This loads the primary aliases for /tag/x and /tag/x/entity_type pages
(for all entity types that support them).

This loads the primary aliases for /user/x/subscriptions/type pages
(for all entity types that support them).

Rather than doing my $lang = $c->stash->{current_language} // 'en';
a lot of times on different files, this sets a current_language attribute
in Server that we can then just call every time we need it.

This loads the primary aliases during load_entities for relationships,
so that for example related works and writers will show the aliases
from a work page.

Still missing: pass $c->current_language from the controller
rather than trying to get it in data which cannot work.

This was not failing right now, but it will when we start loading aliases
for ACs in a subsequent commit. I also cannot see any reason to try it.

We never actually pass a hover, so all passedHover was doing here was
complicate things for no reason. I dropped it.

This makes it simpler to merge the two cases where we show disambiguation
on hover, which makes my brain hurt a bit less (marginally)
and will make it easier to show primaryAlias in a subsequent commit.

This loads the primary aliases for artist credit artists so that they can
be displayed on hover instead of the sortnames when looking at
each artist in the credit.

Still missing: pass $c->current_language from the controller
rather than trying to get it in data which cannot work.