Change all goto page inputs on edit routes page to be the same width

The width of a select input depends on the longest option in the input;
on the edit routes page which has lots of them each with different
options the last select input on the page can end up much less wide than
the others, which is visually distracting.

This commit fixes that issue by using a width override to make each
input take up the full available space of the grid column. This doesn't
take up the full width of the viewport, because of the grid, but is
still a bit wider than strictly necessary; however all the other width
overrides are not wide enough for a question of reasonable length.

Author: lfdebrux

app/views/routes/show.html.erb

@@ -33,7 +33,13 @@
                           route_form.hidden_field(:id) +
                             route_form.hidden_field(:page_id) +
                             route_form.hidden_field(:answer_value) +
-                            route_form.govuk_select(:goto, options_for_select(route_form.object.goto_options, route_form.object.goto), label: route_form.object.label, id: route_form.field_id(:goto))
+                            route_form.govuk_select(
+                              :goto,
+                              options_for_select(route_form.object.goto_options, route_form.object.goto),
+                              label: route_form.object.label,
+                              id: route_form.field_id(:goto),
+                              class: ["govuk-!-width-full"],
+                            )
                         end %>
                       </li>
                     <% end %>