Note using `params[:relatable_type].classify` is recognized as a
security risk by some tools. However, it's a false positive, since we've
added constraints to the URL so that paramenter can only have the values
we trust.
This way screen reader users will be notified that the element is the
current one.
I'm not entirely sure whether `aria-current="page"` is more appropriate
than `aria-current="true"`, since it's a general helper which can be
used for any collection of links.
This way we'll be able to apply it to the SDG icon, which is not
included in font-awesome.
Note we're adding a font-icon selector so it's defined before the
admin-menu-icon selector and so in case of conflicting rules the ones in
the admin-menu-icon selector are used.
This way we simplify the HTML and generating similar menus will be
easier. We also improve the experience for screen reader users, who
might have been hearing the icons as text because we weren't using the
`aria-hidden` attribute.
We're still keeping the "icon-" classes for compatibility with CONSUL
installations which might have changed this code.
From a semantic point of view, there's no reason to add a strong
emphasis to the menu items.
Besides, using CSS simplifies the code and is less error-prone. For
instance, the "stats" section didn't have a <strong> tag, and so it was
the only one which wasn't bold.
