Indicate that links inside labels open in a new window

Most screen readers don't notify when a link is about to open in a new
window [1], so we're indicating it, like we were already doing in most
places with similar links.

We could also add a visual indicator, but since links inside labels
already have accessibility issues, giving more attention to these links
might make matters worse.

[1] https://www.powermapper.com/tests/screen-readers/navigation/a-target-blank/

spec/components/shared/agree_with_terms_of_service_field_component_spec.rb

@@ -18,4 +18,13 @@ describe Shared::AgreeWithTermsOfServiceFieldComponent do
 
     expect(page).to have_css "a[target=_blank]", count: 2
   end
+
+  it "contains links indicating they open in a new window" do
+    render_inline component
+
+    expect(page).to have_link count: 2
+    expect(page).to have_link "Privacy Policy"
+    expect(page).to have_link "Terms and conditions of use"
+    expect(page).to have_link " (link opens in new window)", count: 2
+  end
 end