The `hide` action was calling the `block` method while the `soft_block`
action was calling the `hide` method.
Combined with the fact that we also have a `block` permission which is
used in `ModerateActions` the logic was hard to follow.
Having proper headers makes it more accessible.
We're also using the table actions component because we're going to add
another action. Since table actions use a flex layout, we have to tweak
the styles a little bit. For that, I'm adding a <main> element which
will make it possible to style just this table while also providing an
extra shortcut for people using screen readers.